Summary
The best carbon monoxide detector for most homes is the First Alert CO615: a $39.99 plug-in alarm with battery backup and a backlit display that shows the CO level. (Plug-In Carbon Monoxide Alarm with Battery Backup and Digital Display (CO615)) If you never want to change a battery, get the Kidde COBD10, which runs on a 10-year sealed battery. (Carbon Monoxide Alarm, 10-Year Battery Powered (COBD10))
See the First Alert CO615 ($39.99)
Prices checked on Nov. 14, 2026, on the makers’ own stores. We don’t earn a commission from these stores.
Carbon monoxide has no color and no smell, so an alarm is the only practical warning. Searches for carbon monoxide detectors in the U.S. jump every fall and peaked at 368,000 in January 2026, when furnaces, fireplaces and generators are all running. (Google search volume data for terms) CPSC says to put an alarm on every level of the home and outside sleeping areas. (CO Alarms)
Our top picks
| Pick | Power | Price (Nov. 14, 2026) | |
|---|---|---|---|
| Best overall: First Alert CO615 | Plug-in + battery backup | $39.99 | See it |
| No battery changes: Kidde COBD10 | 10-year sealed battery | Check retailers | See it |
| Tabletop: First Alert CO710 | 10-year sealed battery | $54.99 (Carbon Monoxide Alarm with 10-Year Battery and Digital Temperature Display (CO710)) | See it |
| Budget: First Alert CO400 | Replaceable batteries | $21.99 (Battery Powered Carbon Monoxide Alarm (CO400)) | See it |
| Smoke + CO combo: First Alert SMCO210 | 10-year sealed battery | $54.99 (10-Year Battery 2-in-1 Smoke and Carbon Monoxide Alarm with Slim Profile Design (SMCO210)) | See it |
| Smart: First Alert SC5 Battery | Battery, Wi-Fi app | $129.99 (SC5 Battery Smart Smoke and Carbon Monoxide Alarm) | See it |
How we chose
We started from the government rules: CPSC and the CDC both say to choose battery-operated or battery-backup alarms, and the CDC suggests a digital readout. (Carbon Monoxide Information Center) (Carbon Monoxide Poisoning Basics) Every pick meets the first rule, and four of six have a display. We then picked one alarm for each common setup: an outlet in the hallway, no battery changes, no installation, a tight budget, one ceiling alarm for smoke and CO, and phone alerts. Features and prices come from the makers’ pages on Nov. 14, 2026; we haven’t lab-tested these alarms. More on how we pick.
1. First Alert CO615: best overall
Best for: the hallway outside the bedrooms. Verdict: the simplest way to meet CPSC’s advice, with a readout you can check.
The CO615 plugs into a wall outlet and keeps running on its backup battery if the power goes out. Its backlit screen shows the CO and power levels, and an end-of-life warning tells you when to replace it. That matters in winter storms, when CPSC warns that generators belong outside, at least 20 feet from the house.
- Pros: battery backup; CO readout; one test/silence button.
- Cons: you need a free outlet that isn’t controlled by a light switch.
- Skip it if: the right spot has no outlet. Choose the Kidde COBD10.
Check the CO615 at First Alert ($39.99)
2. Kidde COBD10: best with no battery changes
Best for: anyone who hates low-battery chirps. Verdict: install it and forget the batteries for a decade.
Kidde’s COBD10 runs on a 10-year battery that never needs replacing, so there are no low-battery chirps at night. Its backlit display lights up when you press the button. Kidde sells it through retailers rather than directly, so check the price where you shop.
- Pros: no battery changes; display; mounts anywhere.
- Cons: you replace the whole alarm when the battery ends.
- Skip it if: you want the CO level always on screen. The CO615 shows it full time.
See where to buy the Kidde COBD10
3. First Alert CO710: best tabletop
Best for: renters, guest rooms and trips. Verdict: real protection without drilling a hole.
The CO710 needs no installation: you set it on a table or shelf. It has a sealed 10-year lithium battery and a backlit display that shows the room temperature and the CO level. Our advice: if you rent, ask the landlord which alarms they provide, and add one like this outside your bedroom if there isn’t one.
- Pros: no install; 10-year battery; portable.
- Cons: easy to move out of the right spot.
- Skip it if: small kids or pets might knock it off a shelf.
Check the CO710 at First Alert ($54.99)
4. First Alert CO400: best budget
Best for: covering every level for less. Verdict: the basics at the lowest price.
At $21.99, the CO400 uses an electrochemical sensor and sounds an 85-decibel alarm. It runs on batteries, so it keeps working in an outage. CPSC says to test CO alarms monthly and change the batteries every year.
- Pros: cheapest pick; battery powered; loud.
- Cons: no readout; yearly battery changes.
- Skip it if: you’d rather never change batteries.
Check the CO400 at First Alert ($21.99)
5. First Alert SMCO210: best smoke and CO combo
Best for: the ceiling outside the bedrooms. Verdict: two alarms in one, with no battery changes.
The SMCO210 combines smoke and CO detection in a slim alarm with a 10-year sealed battery. First Alert says its Precision Detection reduces cooking nuisance alarms. CPSC confirms combination alarms are an option. Our advice: a combo covers the hallway rule for both, but each bedroom still needs a smoke alarm. See our smoke detector placement guide.
- Pros: one alarm, two dangers; sealed battery.
- Cons: doesn’t link to your other alarms.
- Skip it if: you want every alarm in the house to sound together. Get the SC5.
Check the SMCO210 at First Alert ($54.99)
6. First Alert SC5 Battery: best smart alarm
Best for: alerts on your phone when you’re away. Verdict: the upgrade for a connected home or an old Nest Protect.
The SC5 sends smoke and CO alerts to your phone through the Resideo Connect app, interconnects with compatible alarms so they all sound together, and uses voice alerts that say the type and location of the danger. First Alert says it’s compatible with and replaces Google’s Nest Protect. CPSC says interconnected alarms are best.
- Pros: phone alerts; interconnect; voice location alerts.
- Cons: $129.99 each; needs Wi-Fi for smart features.
- Skip it if: you just need one alarm in a small apartment.
Check the SC5 at First Alert ($129.99)
How to choose a carbon monoxide detector
Plug-in, 10-year battery or replaceable batteries?
A plug-in with battery backup is the cheapest way to get a full-time readout. A 10-year sealed battery means no chirps and no battery runs. Replaceable batteries cost least up front. Whatever you choose, it has to keep working in an outage. Our pick: the First Alert CO615.
How many to buy
One on every level and one outside each sleeping area. Our carbon monoxide detector placement guide shows the count for common home layouts.
When to replace it
The CDC says to follow the maker’s instructions or replace the detector every five years. Our advice: write the install date on the back with a marker.
If the alarm sounds
CPSC says to get outside to fresh air right away, then call 911. Using a heater this winter? Read our space heater safety guide too.
Final verdict
For most homes, buy the First Alert CO615 ($39.99) for the hallway outside the bedrooms, plus one alarm for every other level. If you want zero battery changes, choose the Kidde COBD10.
- Best overallFirst Alert CO615 Plug-In Carbon Monoxide Alarm with Battery Backup & Digital Display $39.99See pick ↓
- Best no battery changesKidde Carbon Monoxide Alarm, 10-Year Battery Powered (COBD10) —See pick ↓
- Best tabletopFirst Alert CO710 Carbon Monoxide Alarm with 10-Year Battery & Digital Temperature Display $54.99See pick ↓
- Best budgetFirst Alert CO400 Battery-Operated Carbon Monoxide Alarm $21.99See pick ↓
- Best smoke + CO comboFirst Alert SMCO210 10-Year Battery 2-in-1 Smoke & Carbon Monoxide Alarm $54.99See pick ↓
- Best smartFirst Alert SC5 Battery Smart Smoke and Carbon Monoxide Alarm $129.99See pick ↓
Price ranges as last checked; “—” means we couldn’t confirm a current price. Details and sources in each pick.
Why now
U.S. searches for “carbon monoxide detector” rise from about 165,000 a month in summer to 246,000 in October and peaked at 368,000 in January 2026, according to Google Keyword Planner.
CPSC says to put CO alarms on every level of the home and outside sleeping areas, and to choose alarms that keep working in a power outage.
Buy before you switch on the furnace, light the fireplace or plug in a generator, not after the first cold snap.
Each guide separates what the sources show from what we infer. We don’t use countdowns or “selling fast” claims.
Products
- Product photo
First Alert CO615 Plug-In Carbon Monoxide Alarm with Battery Backup & Digital Display
Best for: A hallway outlet outside the bedrooms
Why we like it
- Plugs into any outlet, with battery backup for power outages
- Backlit display shows CO and power levels at a glance
- End-of-life warning when it's time to replace it
Limitations
- Needs a free outlet in the right spot
- Backup batteries still need changing
$39.99Source: First Alert · checked Nov 14, 2026Check price at First Alert - Product photo
Kidde Carbon Monoxide Alarm, 10-Year Battery Powered (COBD10)
Best for: Bedroom hallways where you never want a 3 a.m. low-battery chirp
Why we like it
- 10-year never-replace battery
- Backlit display lights up at the push of a button
- No low-battery chirps at night
Limitations
- Kidde lists retailers instead of selling it directly
- Whole unit gets replaced when the battery ends
Prices change often: check today’s price at Kidde.Check price at Kidde - Product photo
First Alert CO710 Carbon Monoxide Alarm with 10-Year Battery & Digital Temperature Display
Best for: Renters, guest rooms and travel
Why we like it
- No installation: sits on a table or shelf
- Sealed 10-year lithium battery
- Backlit display shows temperature and CO level
Limitations
- Easier to knock over or move out of place
- $54.99, more than the plug-in
$54.99Source: First Alert · checked Nov 14, 2026Check price at First Alert - Product photo
First Alert CO400 Battery-Operated Carbon Monoxide Alarm
Best for: Adding an alarm to every level for less
Why we like it
- $21.99, the cheapest pick
- Electrochemical sensor and an 85-decibel alarm
- Battery powered, so it works in an outage
Limitations
- No digital readout
- Batteries need regular changes
$21.99Source: First Alert · checked Nov 14, 2026Check price at First Alert - Product photo
First Alert SMCO210 10-Year Battery 2-in-1 Smoke & Carbon Monoxide Alarm
Best for: One ceiling alarm that covers both rules outside the bedrooms
Why we like it
- Smoke and CO in one slim alarm
- Sealed 10-year battery, no low-battery chirps
- Designed to cut cooking nuisance alarms
Limitations
- Bedrooms still need their own smoke alarms
- Not interconnected with other alarms
$54.99Source: First Alert · checked Nov 14, 2026Check price at First Alert - Product photo
First Alert SC5 Battery Smart Smoke and Carbon Monoxide Alarm
Best for: Phone alerts when you're away, or replacing a Nest Protect
Why we like it
- Sends smoke and CO alerts to your phone through the Resideo Connect app
- Interconnects so all compatible alarms sound together
- Voice alerts say the type and location of danger
Limitations
- $129.99, the priciest pick
- Needs Wi-Fi and an app for the smart features
$129.99Source: First Alert · checked Nov 14, 2026Check price at First Alert
Why only six picks? We list a product only when we can explain why it helps and where it falls short. We don’t add picks to reach a number.
FAQ
Are plug-in carbon monoxide detectors good?
Yes, if they have battery backup. CPSC recommends CO alarms that keep working in a power outage, which is when people run generators and fuel-burning heaters. The First Alert CO615 plugs in and has battery backup.
How many carbon monoxide detectors do I need?
At least one on every level of the home and one outside each sleeping area, according to CPSC. A two-story house with all bedrooms upstairs needs at least two.
How long do carbon monoxide detectors last?
Follow the maker's replacement date. The CDC says to replace the detector following the maker's instructions or every five years; Kidde says to replace CO alarms every 7 to 10 years.
Questions come from real search data (cpsc-co; cpsc-alarms; cdc). We don’t invent questions.
Sources & method
Who this guide is for
This guide is for anyone buying a first carbon monoxide alarm, replacing an old one, or adding alarms before running a furnace, gas stove, fireplace or generator this winter.
How we picked
- We list a product only when we can explain why it helps and where it falls short.
- We list limitations for every pick, based on product specs and buyer reviews.
- We haven’t tested these products ourselves. When we do, we’ll say so.
- Prices appear only when checked in the last 7 days, with the store and the date shown. Otherwise we leave them out.
Sources
- First Alert — Plug-In Carbon Monoxide Alarm with Battery Backup and Digital Display (CO615) (accessed Nov 14, 2026). Dual-power plug-in with battery backup; backlit display of CO and power levels; test/silence button; end-of-life warning. CO615XP $39.99 on firstalert.com.
- Kidde — Carbon Monoxide Alarm, 10-Year Battery Powered (COBD10) (accessed Nov 14, 2026). 10-year never-replace battery; backlit display at the push of a button; no low-battery chirps; replace CO alarms every 7-10 years. Sold through retailers (Where to Buy).
- First Alert — Carbon Monoxide Alarm with 10-Year Battery and Digital Temperature Display (CO710) (accessed Nov 14, 2026). Tabletop or shelf, no installation; built-in 10-year lithium battery; backlit display of temperature and CO. CO710XP $54.99.
- First Alert — Battery Powered Carbon Monoxide Alarm (CO400) (accessed Nov 14, 2026). Electrochemical sensor; 85-decibel alarm; battery operated; test/silence button. CO400 $21.99.
- First Alert — 10-Year Battery 2-in-1 Smoke and Carbon Monoxide Alarm with Slim Profile Design (SMCO210) (accessed Nov 14, 2026). Low-profile combo alarm; 10-year sealed battery; Precision Detection to reduce cooking nuisance alarms; end-of-life warning. $54.99.
- First Alert — SC5 Battery Smart Smoke and Carbon Monoxide Alarm (accessed Nov 14, 2026). Phone alerts through the Resideo Connect app; interconnect; voice alerts with type and location; compatible with and replaces Nest Protect. $129.99.
- U.S. Consumer Product Safety Commission — CO Alarms (accessed Nov 9, 2026). Install CO alarms on each level and outside sleeping areas; not in attics or basements without a sleeping area; test monthly, change batteries yearly; combination alarms exist.
- U.S. Consumer Product Safety Commission — Carbon Monoxide Information Center (accessed Nov 9, 2026). Battery-operated or battery-backup alarms; interconnected alarms are best; generators at least 20 feet from the house; get outside and call 911 if the alarm sounds.
- Centers for Disease Control and Prevention — Carbon Monoxide Poisoning Basics (accessed Nov 9, 2026). Battery-operated or battery-backup detector near every sleeping area; consider a digital readout; replace the detector per the maker or every five years.
- Google Keyword Planner — Google search volume data for terms: “carbon monoxide detector”, “plug in carbon monoxide detector”, “best carbon monoxide detector”, “smoke and carbon monoxide detector combo” (U.S., accessed Nov 14, 2026).
Review history
- Published Nov 14, 2026.
