The 7 Best Smoke Alarms
Updated by · How we research
Seven smoke and CO alarms compared on sensor type, battery, wiring and linking. The X-Sense SC07 leads with a photoelectric sensor and a sealed battery. When users buy our independently chosen editorial selections, we may earn commissions to help fund the Wiki.
Every smoke alarm wears out: fire safety agencies say to replace it 10 years after the manufacture date printed on its back, even if the test button still makes it beep. If yours are older, or you want carbon monoxide protection too, these are the sealed-battery, hardwired and wirelessly linked alarms worth putting on a ceiling, for owners and renters alike.
Editor's Notes
October 23, 2026, by Ezvid Wiki Admin:
The X-Sense SC07 takes the top spot. It pairs a photoelectric smoke sensor with a carbon monoxide sensor and a battery sealed in for the alarm's whole working life, and it shows the carbon monoxide level on a screen. Most of the old list was gone: Google stopped making the Nest Protect in 2025, the First Alert Onelink Safe & Sound and Kidde KN-COSM-BA have run out of stock for good, and we couldn't find the X-Sense Escape Light, Kidde i9050 or First Alert BRK 7030BSL on sale. The Viwon GS811-A only detects carbon monoxide, and the Kidde KN-COPE-I gives way to Kidde's newer hardwired model. The First Alert BRK 3120B stays for readers who want both sensor types.
To choose, we weighed NIST's full-scale fire tests of photoelectric, ionization and dual-sensor alarms against U.S. Fire Administration placement advice and each model's UL listings. We left out the First Alert SC5, the Nest Protect's successor, because owner feedback on it is poor so far, and we'd rather wait than recommend a shaky smart alarm.
January 28, 2021:
Unsurprisingly, it was a fairly steady round of updates in a very stable category. Our only real substantive changes this time around were removing the CooWoo Battery Powered, which seemed to be suffering from some availability issues, and replacing it with another solid, battery-powered option: the X-Sense SC07 — an affordably priced combination unit with a backlit LCD to keep you advised of ambient carbon monoxide levels.
We also considered adding the Roost PP3 to our list – a smart, nine-volt battery that affords any basic detector the luxury of app connectivity and remote control – but widespread user complaints of software updates rendering the device useless led us to decide against it. By the sounds of things, going forward, the company will only be offering cloud connectivity for their second-generation offering, which was only available direct from the company at the time of this update’s publication.
January 01, 2020:
The majority of existing choices for this category managed to make it through this round of updates. However, we did decide that the First Alert BRK 7010B was bit too pricey to stay, and we removed the Leeo Smart Alert – since the company stopped offering support for the model.
We also added several new selections to these rankings, including the First Alert BRK 7030BSL, a combination detector that incorporates a strobe light into its design, for the benefit of the hearing impaired; the X-Sense Escape Light, which immediately activates an LED emergency light during alarm states; and the First Alert Onelink Safe & Sound, an option with a built-in smart speaker that’s compatible with Apple HomeKit and Amazon Alexa.
A few considerations worth making while you shop:
Photoelectric vs. Ionization: The two basic types of sensors smoke alarms depend on are photoelectric sensors and ionization sensors. Dual-sensor options (which incorporate both types of sensor) are also widely available. While ionization sensors, like the one in the Kidde i9050, do a better job at detecting smoke from larger fires, photoelectric sensors, like the one in the Kidde KN-COPE-I, tend to be superior when it comes to detecting smoke from smoldering fires. Photoelectric sensors seem to be the most popular these days, probably because they’re less susceptible to false alarms via shower steam or burning food.
A note on dual-sensor models:
While dual-sensor models, like the First Alert BRK 3120B, might offer you better peace of mind than a single-sensor alternative, they still have their own problems. Internally, these sensors need to either be wired in series or parallel. If they’re wired in series, both sensors will need to detect smoke before the unit enters an alarm state – which means less false alarms, but a longer response time. Contrastingly, if the sensors are wired in parallel, only one sensor needs to detect smoke for the unit to enter an alarm state – which might mean a shorter response time, but certainly means more false alarms.
Battery-Powered vs. Hardwired: Although I still believe that there’s a place in the world for battery-powered smoke alarms – for instance, in a camper, gazebo or carport – for the most part, hardwired is the way you want to go, if at all possible. Besides reducing the frequency of battery swaps (they do still have backup batteries that will need to be changed every few years, or in some cases are just rated to last the recommended life of the smoke alarm), the biggest benefit of hardwired alarms is the fact they can be connected throughout your home. In this manner, smoke detected in your basement will activate alarms on the second floor of your home, giving you and your family a chance to get to safety before the smoke makes it all the way up to your sleeping quarters.
It’s also worth mentioning that many modern building codes demand hardwired smoke detectors be installed in new homes – and often several of them. So, if you are still considering a battery-powered option, do your due diligence and make sure that you’re not accidentally allowing a building code infraction that could potentially affect your insurance coverage.
Versatility: Smoke alarms are important, but so are carbon-monoxide alarms, and with so many excellent combination options on the market – like the battery-powered Viwon GS811-A and the hardwired First Alert BRK 7030BSL – why not kill two birds with one stone?
Advanced options like the Nest Protect 2nd Generation and First Alert Onelink Safe & Sound are designed to connect with your home’s smart system, and offer further opportunities for versatility through additional features like built-in night lights and speakers.
Special Honors
American Red Cross Sound the Alarm The Red Cross and local partners install free smoke alarms in homes that need them, check the ones already up and help families plan an escape route. Availability depends on where you live; its page takes a ZIP code to find a local visit or event. redcross.org
Photoelectric, Ionization Or Both
An ionization sensor reacts to the tiny particles from fast, flaming fires, and it's also the type most likely to go off over toast.
Home smoke alarms sense smoke in one of two ways. A photoelectric sensor shines a light into a small chamber and reacts when smoke scatters it, which makes it quicker on slow, smoldering fires, like a cigarette dropped into a couch. An ionization sensor reacts to the tiny particles from fast, flaming fires, and it's also the type most likely to go off over toast. The U.S. Fire Administration says nobody can predict which kind of fire they'll have, so it recommends both types in a home or dual-sensor alarms.
In NIST's full-scale fire tests, dual-sensor alarms sounded sooner on average than either single type, but their lead over photoelectric alarms was small, about half a minute in one test series. The International Association of Fire Fighters prefers photoelectric alarms for that reason and because ionization units cause more nuisance alarms. A dual-sensor alarm such as the First Alert BRK 3120B fits a hallway away from the stove; photoelectric alarms suit bedrooms and spots near the kitchen.
Newer editions of UL 217, the main U.S. smoke alarm standard, add a cooking-smoke test meant to cut false alarms. A NIST technical note cautions that the test won't stop every nuisance alarm, so placement still matters.
Sealed Battery, AA Cells Or House Power
Battery-only alarms come in two kinds. Sealed alarms carry a lithium battery meant to last the alarm's full 10-year life; when it chirps at the end, the whole alarm gets replaced. Alarms with AA or 9-volt cells let you swap batteries, but the U.S. Fire Administration says to change them at least once a year, and a battery pulled to stop a chirp is how many alarms end up dead. California and New York generally require sealed batteries in battery-only smoke alarms, as Google's Nest help page summarizes, so check local rules, especially for rentals.
Hardwired alarms run on house power, with a backup battery for outages. They're common in newer homes, where codes often call for wired, linked alarms. A new alarm may need a different wiring plug than the old one, and running new wiring is a job for a qualified electrician.
Whatever the power source, every alarm wears out. Replace it 10 years after the manufacture date printed on its back. A combination alarm also sounds an end-of-life warning when its carbon monoxide sensor is spent, and that means a new alarm, not a new battery.
Placement, And Why Linked Alarms Matter
Put a smoke alarm in every bedroom, outside each sleeping area and on every level, basement included, as Kidde's summary of NFPA guidance lays out. Mount it on the ceiling or high on a wall, and keep it about 10 feet from the stove so cooking doesn't set it off (SafeWise).
Carbon monoxide alarms belong on every level and outside sleeping areas, especially in homes with gas appliances, a fireplace or an attached garage. A combination alarm covers both jobs from one spot. The NFPA has more on carbon monoxide safety.
Linked alarms all sound when one detects trouble, so a fire in the basement wakes someone upstairs, and fire agencies recommend them. Hardwired alarms link through a third wire, while wireless sets such as the X-Sense XP0H-WN link by radio. Most brands link only with their own models, so it pays to stick with one brand throughout a home.
How we researched this
We compared 23 current smoke and combination alarms from X-Sense, Kidde, First Alert, Siterwell, Heiman and Google, read the makers' specifications and safety-standard listings, NIST fire test reports and U.S. Fire Administration guidance, analyzed owner feedback, and checked every brand against the Consumer Product Safety Commission's recall records. Updated October 23, 2026 by Ezvid Wiki Admin.
Sources (14)
- X-Sense: smoke and CO alarms
- Kidde: home safety products
- First Alert: alarms
- NIST: performance of dual photoelectric/ionization smoke alarms in full-scale fire tests
- NIST Technical Note 2305
- U.S. Fire Administration: smoke alarms
- Kidde: placement of smoke alarms
- SafeWise: smoke alarm buyer's guide
- Bob Vila: best smoke detectors
- Google Nest Help: smoke alarm laws in California and New York
- NFPA: carbon monoxide
- EPA RadTown: americium in ionization smoke detectors
- American Red Cross: Sound the Alarm
- CPSC: recalls
Frequently asked questions
How long do smoke alarms last?
Ten years from the manufacture date printed on the back. Replace the alarm then, even if it still beeps when tested. Combination alarms also warn when the carbon monoxide sensor reaches the end of its life.
How many smoke alarms do I need?
One in every bedroom, one outside each sleeping area and at least one on every level, including the basement. Larger homes may need more.
Why does my smoke alarm keep chirping?
A chirp every minute or so usually means a low battery. On a sealed 10-year alarm it means the alarm has reached end of life and needs replacing. Many alarms use different chirp patterns for low battery, end of life and faults, so check the manual.
Is a smart smoke alarm worth it?
It adds phone alerts when you're away, but it depends on your Wi-Fi and the maker's app. Google stopped making the Nest Protect in 2025, and First Alert's SC5 took its place in Google's lineup. Any listed alarm will wake you at home; a smart one mainly helps when nobody's there.
Are ionization smoke alarms safe to keep in the house?
Yes. They hold a tiny amount of americium, and the EPA says they pose no health threat when left intact and used as directed. Don't take one apart, and ask your fire department how to dispose of old ones.
Have any of these alarms been recalled?
We found no recalls for the models on this list in the Consumer Product Safety Commission's records. Kidde's 2021 recall covered its older TruSense alarms, which aren't listed here.
