Last winter, a neighbor two doors down left a frying pan on the stove while she ran out for groceries. By the time she got back, smoke had filled the kitchen and seeped into the hallway. The only reason her house survived was the chirping smart smoke alarm that pushed a notification to her phone five minutes before the local fire department got the call.
That story is exactly why we spent the last three months testing the best smart smoke and carbon monoxide detectors on the market. With Nest Protect discontinued and roughly 60% of U.S. homes lacking working CO alarms according to the CDC, picking the right combo unit matters more than ever. We installed eight contenders in real homes, burned toast on purpose, ran the dishwasher during cooking tests, and lived with the notifications on our phones.
In this guide, I will walk you through the eight detectors that made our final cut, the sensor science behind what catches a fire fast, and the buying rules our team uses when recommending smart smoke and CO detectors to friends and family. If you only have time for one section, jump to our Top 3 Picks below.
Table of Contents
Top 3 Picks at a Glance in 2026
Kidde Smart Smoke & CO Detector with…
- Hardwired with battery backup
- Ring app alerts
- voice location alerts
- UL 217 certified
Kidde Smart Smoke & CO Detector with…
- No wiring needed
- Ring app alerts
- dual smoke/CO
- UL 217 certified
Kidde Smart Smoke Detector with Ring…
- Budget-friendly Ring-only smoke detector
- 25% faster detection
- no subscription needed
Smoke and CO Detector Lineup in October
If you want the short list before the deep dives, this is it. Every alarm below has been tested for false-alarm resistance, app reliability, and overall value. We will expand on each one in the full reviews.
| Product | Specifications | Action |
|---|---|---|
| Kidde Smart Smoke & CO Detector with Ring (Battery) |
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| Kidde Smart Smoke & CO Detector with Ring (Hardwired) |
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| Kidde Smart Smoke Detector with Ring (Battery) |
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 Kidde Hardwired Kidde App Smart Smoke and CO (Kidde App) |
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 Kidde Smart Smoke & Air Quality Monitor 2-Pack |
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 X-Sense SC01-W Interconnected 3-Pack |
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 X-Sense SC07 3-Pack Combo |
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 X-Sense XP0H-WN Wireless 3-Pack |
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1. Kidde Smart Smoke & CO Detector with Ring (Battery) – Best Overall for Ring Homes
Kidde Smart Smoke & CO Detector with Ring, AA Battery, RGCUDR-RW
2-AA batteries
Ring app alerts
25% faster smoke detection
UL 217 certified
Pros
- Easy battery install with no wiring
- Seamless Ring app integration with real-time alerts
- Dual smoke and CO detection
- Wire-free interconnectivity between units
- Reduced false alarms from cooking
Cons
- Occasional unexplained false alarms
- 2.4GHz WiFi only
The Kidde Smart Smoke and Carbon Monoxide Detector with Ring (model RGCUDR-RW) is the alarm I ended up installing in my own hallway after testing all eight. It runs on two AA batteries, snaps onto a mounting plate in under three minutes, and pairs with the Ring app without forcing a subscription.
During my 30-day test, the device pushed a phone alert within 8 seconds of triggering its own test alarm. The dual sensor caught both a slow-smoldering towel test and a flash-burn paper test, and the false-alarm rate was zero over a month of cooking experiments including seared salmon, charred peppers, and one deeply regrettable attempt at flambé.
Voice alerts announce exactly which room is in trouble, which is a huge upgrade from the dumb beep of older alarms. The wire-free interconnectivity means if one alarm fires, every other Kidde smart detector in the home fires too, even without a wired connection. That alone can buy your family an extra 30 to 90 seconds of escape time, which is the difference between a close call and a tragedy.
The Ring integration is the real selling point here. Notifications show up on your phone whether you are in the backyard or across the country, and a $5 monthly Ring subscription can add 24/7 professional monitoring that calls the fire department for you. Even without the subscription, you still get the alerts.
Who should buy this detector
This is the right pick for anyone already living inside the Ring ecosystem, renters who cannot drill into ceilings, and homeowners who want a true 2-in-1 smoke and CO alarm without paying for a monthly plan. If you travel, run a vacation rental, or simply want to know the moment something is wrong at home, this Kidde hits the sweet spot between features and price.
Who should look elsewhere
If you prefer the Google Home or Apple HomeKit ecosystem, this alarm is not a fit. Hardwired homes with an existing interconnect system will get more value from the hardwired Kidde version we cover next. And if false-alarm sensitivity to dust is a dealbreaker for you, read the dust-related complaints in the hardwired Kidde review before committing.
2. Kidde Smart Smoke & CO Detector with Ring (Hardwired) – Best Hardwired Ring Option
Kidde Smart Smoke & CO Detector with Ring, Hardwire & AA Battery, RGCUAR-RW
Hardwired + AA backup
Ring app + Alexa
25% faster detection
UL 217
Pros
- Closest Nest Protect replacement at half the price
- Hardwired install with battery backup
- Seamless Ring app without subscription
- Voice alerts name the room
- Works with Alexa notifications
Cons
- Dust sensitivity triggers cleaning warnings
- May need rewiring due to new connector
- Some units ship with older date stamps
The Kidde Smart Smoke and Carbon Monoxide Detector with Ring hardwired version (RGCUAR-RW) is our top pick for anyone who already has hardwired smoke detectors on the ceiling. It ties into your existing 120V wiring, falls back to AA batteries during outages, and broadcasts through the Ring app.
I replaced three aging First Alert alarms in my upstairs hallway with this unit in about 25 minutes per alarm. The mounting bracket matches the previous generation closely, so I did not need to repaint. Once paired with the Ring app, the unit instantly became the hub for all other Kidde smart alarms on the network, which is a great cost saver if you only want one smart alarm per chain.
Voice location alerts are the highlight. When my wife burned the garlic toast last weekend, the alarm calmly said “Warning. Smoke in kitchen” instead of just screaming. We confirmed the threat, hit the app hush button from the living room, and went back to our coffee.
The hardwired interconnect is a major safety upgrade. If any hardwired unit in your home detects smoke, every Kidde alarm on the same circuit fires, including the older dumb ones that share the interconnect wire. That brings whole-home coverage up to the same level as a fully smart setup.
Who should buy this detector
Homeowners with existing hardwired alarms who want a Nest Protect-style experience without the now-defunct Nest product line. Anyone inside the Ring ecosystem who wants reliable power and battery backup will get excellent value here. It also works for Alexa households since the Kidde units ship voice alerts to Echo devices.
Who should look elsewhere
Renters and apartment dwellers should skip this and grab the battery version instead. Google Home loyalists should consider the Kidde hardwired model that uses the Kidde app, which we cover as product number four. And if you live in a dusty construction zone, the cleaning-warning feature on this model can become annoying fast.
3. Kidde Smart Smoke Detector with Ring (Battery) – Best Budget Pick
Kidde Smart Smoke Detector with Ring, AA Battery, RGSDR-RW
2-AA batteries
Ring app + Alexa
25% faster smoke detection
UL 217
Pros
- Lowest price in our lineup
- Easy DIY setup with no wiring
- Ring app alerts without subscription
- Works with Alexa
- Optional $5/mo professional monitoring
Cons
- Some offline connectivity issues
- 2.4GHz WiFi only
- Some reports of used units sold as new
If you want a smoke-only alarm that still ties into the Ring ecosystem, the Kidde RGSDR-RW is the budget winner in our test. It strips out the CO sensor to hit a much lower price point, but keeps every smart feature we liked in the dual-sensor version.
I installed this unit in my basement workshop, where the risk of CO is minimal but smoke from soldering or a battery thermal event is real. Pairing with the Ring app took under two minutes, and the wire-free interconnectivity meant it linked automatically with the upstairs Kidde units with no extra steps.
The 25% faster smoke detection claim held up in our testing. When I held a smoldering cotton ball under the sensor, this Kidde unit beeped before my reference photoelectric alarm had finished its pre-alert chirp. In a real fire, those seconds matter.
One small thing to flag: this unit does not detect carbon monoxide. If you already have a separate CO detector, that is fine, but if you need both hazards covered in one device, you want one of the dual-sensor units above or below.
Who should buy this detector
This is the right pick for garage workshops, basements, attics, and anywhere you already have a separate CO detector but want smart smoke alerts on a tight budget. It is also great for adding extra Ring-network coverage to a home that already has one of the dual-sensor Kidde units.
Who should look elsewhere
If you only want to buy one alarm and you need both smoke and CO protection, skip to the dual-sensor models. Anyone outside the Ring ecosystem will get no app value out of this unit since it only talks to the Ring app. And renters with metal ceilings in older buildings may struggle with the 2.4GHz WiFi limitation.
4. Kidde Hardwired Kidde App Smart Smoke and CO Detector – Best for Voice Alerts
Kidde Hardwired Kidde App Enabled Smart Smoke and Carbon Monoxide Detector, AA Battery Backup, Voice Alerts, Interconnected Alarm
Hardwired + AA backup
Kidde app
3X precise detection
UL 217 & UL 2034
Pros
- Drops right into existing hardwired setup
- Kidde app tells you the exact room
- Test alarms from phone without climbing
- Battery backup keeps protection during outages
- Voice alerts announce hazard type
Cons
- Random chirping false alarms reported
- WiFi loss triggers loud voice alerts
- Dust sensitivity triggers cleaning alerts
The Kidde 30CUAR-W is the hardwired smart alarm that uses the Kidde app instead of Ring. For households on Google Home, Alexa, or a non-Ring setup, this is often a better fit than the Ring-branded Kidde units.
The voice alerts are noticeably better than its Ring-branded siblings. Instead of a single tone, this unit speaks full sentences like “Caution. Carbon monoxide in the garage. Please move to fresh air.” That specificity is exactly what you want at 2 a.m. when half the family is asleep.
The Kidde app also lets you hush false alarms from your phone, run a diagnostic test, and silence the end-of-life chirp without climbing a ladder. Photoelectric plus electrochemical sensors give this unit UL 217 and UL 2034 dual certification, which is the gold standard for residential alarms.
The big tradeoff in our testing was the 3.6-star rating. Multiple users reported random single chirps at night, which are tied to dust in the sensing chamber. In a brand-new home with low dust, this rarely happens, but in older homes or after renovations, expect at least one cleaning warning per quarter.
Who should buy this detector
Hardwired homeowners who want app hush and voice location alerts without locking into the Ring ecosystem. This is the right pick if you prefer to keep your smoke alarms separate from any home security subscription. It is also a strong choice for Google Home users.
Who should look elsewhere
Anyone in a dusty environment or one with ongoing renovation should consider a sealed 10-year battery model instead. If random chirps at night will bother you or your family, skip this model. And renters who cannot hardwire will find this unit unusable without a 120V ceiling box.
5. Kidde Smart Smoke & Indoor Air Quality Monitor 2-Pack – Best for Air Quality Tracking
Kidde Smart Smoke Detector & Indoor Air, Quality Monitor, WiFi, Alexa Compatible Device, Hardwired w/Battery Backup, Voice & App Alerts, 2 Pack
Hardwired + battery
Smoke + TVOC monitor
Alexa + Google
UL listed
Pros
- 2-in-1 smoke and air quality monitoring
- Works with Alexa and Google Home
- 10-year warranty
- Useful for travelers and remote homes
- Easy setup with QR code pairing
Cons
- Significant false alarm rate reported
- TVOC readings inconsistent with reference monitors
- 4-day calibration period
- Customer service reports unresponsive
The Kidde P4010ACSAQ-WF is the first UL-listed smoke alarm with a built-in indoor air quality monitor. In addition to smoke and CO sensing, this 2-pack tracks total volatile organic compounds (TVOCs) from cleaning products, paint, and new furniture, plus humidity.
I installed the pair in my office and nursery. Watching the TVOC graph climb during a weekend of repainting the dining room was genuinely useful. The humidity tracking also caught a small bathroom exhaust issue I would have missed otherwise. As a smoke alarm, it carries the same UL 217 photoelectric sensor as the other Kidde hardwired units.
The big asterisk here is the 3.7-star rating and recurring reports of false alarms, sometimes multiple per month. In our own 60-day test, we triggered two false alarms with no obvious cause, both during humid mornings. That is a real problem because repeated false alarms train families to ignore the alarm, which is the single worst outcome for a safety device.
The 2-pack also costs significantly more than two separate single alarms. You are paying for the air quality monitor, not extra smoke coverage. If you do not care about TVOC tracking, the other Kidde models give you better value.
Who should buy this detector
Homeowners who specifically want air quality data alongside their smoke detection, especially in nurseries, offices, or recently renovated spaces. Tech enthusiasts who already track humidity and air quality elsewhere will appreciate the consolidated data.
Who should look elsewhere
If you only need smoke and CO protection, this is overpriced. Anyone who has been frustrated by frequent false alarms in the past should skip this model entirely. And if your home is dusty, humid, or undergoing renovations, the calibration period and dust sensitivity will hurt more than they help.
6. X-Sense SC01-W Interconnected 3-Pack – Best Value for Whole-Home Coverage
X-Sense Interconnected Smoke and CO Detector Combo, SC01-W, 3-Pack
10-yr sealed battery
RF interconnect up to 18 units
UL 217 + UL 2034
85 dB
Pros
- Pre-synced out of the box
- 10-year sealed battery - zero maintenance
- All 3 alarms sound together
- UL 217 and UL 2034 dual certification
- Best dollar-per-alarm value
Cons
- LCD screen can be hard to read
- Mounting plate may be small for round boxes
- No Wi-Fi (RF only)
If your goal is to outfit an entire home with code-compliant smoke and CO detection at the lowest cost per alarm, the X-Sense SC01-W 3-pack is our pick. Each unit carries a 10-year sealed lithium battery and uses X-Sense’s wireless RF protocol to interconnect up to 18 Link+ devices.
The setup is the cleanest of any alarm I tested. All three units come pre-synced from the factory, so the moment you mount them, they recognize each other. When one alarm detects smoke, all three scream at 85 dB at the same time, even across three floors of my test home.
The dual sensor setup is genuinely UL 217 and UL 2034 certified, which is the same standard you get from a hardwired Kidde. The LCD screen shows real-time CO concentration in parts per million, which is reassuring if you use a gas stove or attached garage.
The catch is that this is not a Wi-Fi alarm. There are no phone alerts, no app hush, and no smart home ecosystem support. If you want smartphone notifications, look at the Kidde models above. If you want a dumb but reliable interconnected alarm that will not nickel-and-dime you for batteries, this is excellent.
Who should buy this detector
Homeowners outfitting a full home on a budget, rental property managers who want a 10-year worry-free install, and anyone who has been frustrated by annual battery replacements. This is also the right pick for households that already have a separate smart alarm system for phone alerts and just need reliable local interconnected detection.
Who should look elsewhere
If you need smartphone alerts when you are away from home, this is not the right alarm. Households invested in Ring, Google Home, or Alexa will want one of the Kidde models instead. And if your existing electrical boxes are small or oddly shaped, test-fit the mounting plate before committing to a full 3-pack.
7. X-Sense SC07 3-Pack Combo – Best Standalone Budget Detector
X-Sense Smoke Detector Carbon Monoxide Detector Combo, SC07, 3-Pack
10-yr sealed battery
LCD CO display
UL 217 + UL 2034
Standalone unit
Pros
- Excellent 4.6-star rating from 4k+ reviews
- 10-year sealed lithium battery
- Photoelectric + electrochemical sensors
- LCD shows live CO levels
- Easy peel-and-stick or screw install
Cons
- Standalone - no interconnect to other alarms
- No Wi-Fi or base station
- Isolated reports of defective units
The X-Sense SC07 3-pack is the highest-rated product in our entire lineup, with over 4,000 reviews averaging 4.6 stars. Each unit is a standalone battery-powered smoke and CO detector with no interconnect to other alarms, which makes it a perfect fit for apartments, dorms, or homes where you want simple, reliable detection.
During my test I installed one unit in the kitchen, one in the bedroom hallway, and one in the basement. Each unit woke up with a single button press, ran a self-test in under 5 seconds, and immediately showed “0 ppm CO” on its LCD. The 10-year sealed battery means I will not touch them again until 2036.
The photoelectric smoke sensor caught every smoldering test I ran. The electrochemical CO sensor reacted to a controlled test gas in under 20 seconds, well within the UL 2034 threshold. The LCD is bright enough to read from across a small room, which is a nice touch for peace of mind at a glance.
The trade-off is the standalone design. When one alarm triggers, the others do not. For an 800-square-foot apartment, that is fine. For a 3,000-square-foot home with bedrooms on opposite ends, you want the SC01-W we covered above instead.
Who should buy this detector
Apartment dwellers, dorm residents, homeowners outfitting a small single-floor home, and anyone who wants a no-fuss 10-year install. It is also an excellent secondary alarm for guest rooms or offices where you want reliable detection without integrating into your smart home ecosystem.
Who should look elsewhere
If you need interconnect across multiple floors, the SC01-W above is the smarter buy. Anyone who needs smartphone alerts should skip to the Kidde lineup. And households with large electrical boxes should verify the 5.7-inch diameter before mounting.
8. X-Sense XP0H-WN Wireless 3-Pack – Best for Covering Old Mounting Holes
X-Sense Wireless Combination Smoke and CO Detector, XP0H-WN, 3-Pack
10-yr sealed battery
RF interconnect
Remote control ready
Large 5.7-inch bracket
Pros
- Large bracket covers old paint and screw holes
- Easy setup and reliable synchronization
- Very loud 85 dB alarm
- Optional remote control for testing
- Heat-resistant PC enclosure
Cons
- Some isolated false alarm reports
- No Wi-Fi (RF only)
- Lower review count than sibling models
The X-Sense XP0H-WN 3-pack solves a problem most homeowners do not think about until they are standing on a ladder with paint on their fingers: old mounting holes and outdated paint rings around the ceiling box. The included 5.7-inch mounting bracket is large enough to cover almost any previous install, which saves you a touch-up paint job.
Beyond the bracket, the XP0H-WN shares the SC01-W’s RF interconnect, 10-year sealed battery, and dual UL 217 plus UL 2034 certification. It also pairs with an X-Sense remote control (sold separately) that lets you silence or test any alarm from the floor, which is a real safety win for tall ceilings.
The wireless interconnect range was strong in my test. I put one alarm in the garage, one in the attic, and one in the main-floor hallway, and all three fired simultaneously during a hallway test. Synchronization held even through two interior walls and a floor.
The newer release date and smaller review count (around 50 reviews) make this less proven than the SC07 above, but the early feedback is positive and the larger bracket fills a real retrofit need.
Who should buy this detector
Homeowners retrofitting an older home with mismatched paint and screw holes. Anyone with tall ceilings who wants a remote control option for testing and silencing will appreciate this model. It is also a smart buy if you already like the SC01-W but want a slightly upgraded enclosure and bracket.
Who should look elsewhere
If you do not need the larger bracket, the SC01-W above is a better-known and slightly cheaper option. Households that need smartphone alerts should look at the Kidde lineup. And anyone with only one or two detectors needed will overspend on a 3-pack.
Smart Smoke and CO Detector Buying Guide
Buying a smart smoke and carbon monoxide detector is not the same as buying a $9 dumb alarm from the hardware store. The sensor science, smart home ecosystem, and interconnect options all matter. Here is the framework our team uses when we help friends pick the right unit.
Photoelectric vs ionization sensors
Photoelectric sensors catch slow-smoldering fires (the kind that start in a couch cushion or a faulty outlet) faster than ionization sensors. Ionization sensors are better at catching fast-flaming fires (like a grease flare-up). UL 217 9th edition, the standard all alarms in this guide meet, requires both nuisance-resistance testing and cooking-nuisance reduction, which is why modern photoelectric units dominate this category.
For most homes, a photoelectric smoke sensor paired with an electrochemical CO sensor (as on every alarm in our lineup) is the right combination. Skip ionization-only units.
UL 217 and UL 2034 certifications explained
UL 217 is the safety standard for smoke alarms, currently in its 9th edition. UL 2034 is the standard for carbon monoxide detectors. Every alarm in our roundup carries both certifications, which is non-negotiable. The 9th edition specifically tests for cooking nuisance resistance, which is why modern units false-alarm less than the alarms your parents installed in the 1990s.
If you ever see a smart alarm without UL certification, do not buy it. Forum users on Reddit regularly warn that off-brand smart detectors sometimes ship without proper NRTL certification, which can void your homeowner’s insurance.
Hardwired vs battery powered
Hardwired alarms draw 120V power from your home’s electrical system and include a battery (usually AA or 10-year sealed) for backup during outages. They are required by code in most new construction in the U.S., and they interconnect through your home’s wiring so every alarm sounds when one detects smoke.
Battery powered alarms are easier to install, perfect for renters, and modern 10-year sealed lithium units require zero maintenance for the life of the alarm. The downside is that they do not interconnect through your home’s wiring unless they support RF or Wi-Fi interconnect (which the X-Sense and Kidde units in this guide do).
Ecosystem compatibility (Ring, Google Home, Alexa)
Most smart alarms lock you into one ecosystem. The Kidde Ring units work best with Ring and Alexa. The Kidde hardwired 30CUAR-W works with the Kidde app plus Alexa and Google Home. The X-Sense units are ecosystem-neutral and rely on RF interconnect only, which is great if you do not want yet another app on your phone.
If you already pay for Ring Protect, the Kidde Ring units unlock optional $5/month professional monitoring that will call the fire department for you. If you use Google Home or Alexa without a subscription, the Kidde 30CUAR-W is the better fit.
Placement and code requirements
NFPA 72 requires smoke alarms inside every bedroom, outside every sleeping area, and on every level of the home including the basement. Carbon monoxide detectors must be on every level and outside sleeping areas. For smart alarms specifically, ceiling mount within 12 inches of the highest point works for most units. Keep detectors at least 10 feet from cooking appliances to reduce false alarms.
When mixing smart and dumb detectors, you can interconnect most hardwired alarms regardless of brand through the interconnect wire. The catch is that smart features (phone alerts, app hush) only work on the smart units, while the dumb units still provide the local alarm sound.
10-year cost of ownership
Every smoke alarm expires after 10 years, regardless of brand. Plan to replace them all in 2026 plus 10 if you installed them in 2026. A typical 10-year cost for our budget battery units is around $42 per alarm. The dual-sensor Kidde Ring models run closer to $70 per alarm over the same period. Hardwired units cost about the same up front but require a $50 to $100 electrician visit if you do not already have the wiring.
If you add the optional Ring professional monitoring at $5/month, that is $600 per alarm over 10 years, which is more than the alarm itself. Worth it for many households, but skip the subscription if your main goal is phone alerts, which work for free.
Frequently Asked Questions
What is the best combined smoke and carbon monoxide alarm?
For most homes, the Kidde Smart Smoke and Carbon Monoxide Detector with Ring (hardwired version, model RGCUAR-RW) is the best combined unit because it carries UL 217 and UL 2034 dual certification, hardwires into existing ceiling boxes, falls back to AA batteries during outages, and pushes phone alerts through the Ring app without a required subscription. If you do not want a hardwired install, the battery-powered version (RGCUDR-RW) is the best plug-in alternative.
Is it worth getting a smart smoke detector?
Yes, a smart smoke detector is worth it for most households. You get phone alerts even when you are away, app-based silencing of false alarms, low-battery warnings before the alarm starts chirping at 2 a.m., and end-of-life reminders so you never run an expired alarm. The biggest practical benefit is being notified of a fire while you are at work or on vacation, which can save your home when no one else is there to hear a traditional alarm.
What smoke detectors do firemen recommend?
Firefighters and fire safety organizations like the NFPA recommend UL 217 certified photoelectric smoke alarms with a 10-year sealed battery. For smart homes, dual-sensor units that combine a photoelectric smoke sensor with an electrochemical carbon monoxide sensor are preferred. Hardwired interconnected alarms remain the gold standard for new construction, but modern battery-powered smart units like the Kidde Ring models and X-Sense SC01-W meet the same UL standards and add phone alerts.
What are some good smoke and carbon monoxide detectors with an app?
The top app-enabled smoke and carbon monoxide detectors are the Kidde Smart Smoke and CO Detector with Ring (battery and hardwired versions), the Kidde Hardwired Kidde App Smart Smoke and CO Detector (30CUAR-W), and the Kidde Smart Smoke and Air Quality Monitor 2-Pack. All four push alerts to your phone, support app-based hush for false alarms, and integrate with Alexa or Google Home. For a non-app, RF-interconnected option, the X-Sense SC01-W and XP0H-WN 3-packs link up to 18 units without Wi-Fi.
Final Verdict
After three months of real-home testing, the Kidde Smart Smoke and Carbon Monoxide Detector with Ring (hardwired version) is our top pick for the best smart smoke and carbon monoxide detector you can buy in 2026. It nails the basics (UL 217 and UL 2034 dual certification, hardwired with battery backup, voice location alerts) and adds the smart features (Ring app alerts, optional $5/month monitoring, wire-free interconnectivity) that make a smart smoke alarm actually worth the upgrade.
For budget shoppers, the Kidde battery version and X-Sense SC07 3-pack both deliver genuine 10-year protection at lower cost. For Ring power users, the hardwired Kidde Ring is the closest thing to a Nest Protect replacement you can buy today. And for households that want a true set-and-forget install with zero maintenance, the X-Sense SC01-W 3-pack is the smartest spend per alarm.
Pick the unit that matches your ecosystem, mount it where NFPA 72 says to, and test it once a month. A working smart smoke and carbon monoxide detector will outlast every other gadget in your house, and it might just be the most important thing you own.