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The best carbon monoxide detector warns you early about an odorless, colorless gas, with a loud alarm, a reliable power source and a clear end-of-life signal.
We compared 8 popular CO alarms by power source, display, alerts, listed standards and maker warranty.
Quick Answer: The Best Carbon Monoxide Detector
- Best Overall: Kidde Carbon Monoxide Detector, Plug-in with AA Battery Backup, 85 dB Alarm, 3rd Edition
- Best Digital Display: First Alert Plug in Carbon Monoxide Alarm with Digital Display CO615
- Best 10-Year Battery: Kidde Carbon Monoxide Detector, 10-Year Battery, Digital Display, 3rd Edition
- Best Budget: First Alert Battery Carbon Monoxide Alarm CO400
- Best Smoke and CO Combo: Kidde Smoke & Carbon Monoxide Detector, 10-Year Battery, 30CUD10
- Best Smart CO Alarm: Kidde Smart CO Detector + Indoor Air Quality, Plug-in & AA Battery, COPDLQW
- Best Interconnected Set: X-Sense Wireless Combination Smoke and CO Detector, XP0H-WN, 3-Pack
- Best CO and Gas Alarm: Kidde Carbon Monoxide + Explosive Gas Alarm, Plug-in with 9V Battery Backup, Digital Display
The Kidde Plug-In CO Detector (AA Backup) is our best carbon monoxide detector for most homes. The First Alert CO615 Digital CO Alarm shows CO levels, and the Kidde 10-Year Battery CO Detector, Digital needs no battery changes.
Best Carbon Monoxide Detector Comparison Table
| Product | Best For | Type | Key Feature | Buy |
|---|---|---|---|---|
| Kidde Carbon Monoxide Detector, Plug-in with AA Battery Backup, 85 dB Alarm, 3rd Edition | Best Overall | Plug-in CO alarm | 120V plug-in, 2-AA backup, peak level memory | Check Price |
| First Alert Plug in Carbon Monoxide Alarm with Digital Display CO615 | Best Digital Display | Plug-in CO alarm, digital | Digital display, peak level, battery backup | Check Price |
| Kidde Carbon Monoxide Detector, 10-Year Battery, Digital Display, 3rd Edition | Best 10-Year Battery | Battery CO alarm, digital | Sealed 10-year lithium battery, display updates every 15 s | Check Price |
| First Alert Battery Carbon Monoxide Alarm CO400 | Best Budget | Battery CO alarm | Electrochemical sensor, 85 dB | Check Price |
| Kidde Smoke & Carbon Monoxide Detector, 10-Year Battery, 30CUD10 | Best Smoke and CO Combo | Smoke and CO combo | 10-year battery, UL 217 and UL 2034 | Check Price |
| Kidde Smart CO Detector + Indoor Air Quality, Plug-in & AA Battery, COPDLQW | Best Smart CO Alarm | Smart plug-in CO alarm | Wi-Fi alerts, low-level CO, IAQ | Check Price |
| X-Sense Wireless Combination Smoke and CO Detector, XP0H-WN, 3-Pack | Best Interconnected Set | Interconnected smoke and CO | Wireless interconnect, 10-year batteries | Check Price |
| Kidde Carbon Monoxide + Explosive Gas Alarm, Plug-in with 9V Battery Backup, Digital Display | Best CO and Gas Alarm | Plug-in CO and gas alarm | Detects CO plus natural gas and propane | Check Price |
The 8 Best Carbon Monoxide Detectors
Each pick below was compared on sensor type, power source, alerts, certification and value.
Kidde Carbon Monoxide Detector, Plug-in with AA Battery Backup, 85 dB Alarm, 3rd Edition
1The Kidde plug-in CO detector runs from a standard 120V outlet with two AA batteries as backup during outages.
👍 Pros & Cons
Pros
- Plug-in with 2-AA battery backup
- Peak Level Memory
- Test-Hush button
Cons
- No digital readout
📄 Detailed Review
- Type: Plug-in CO alarm
- Includes: Alarm + 2 AA batteries
- Key feature: 120V plug-in, 2-AA backup, peak level memory
It sounds an 85 dB alarm, and Peak Level Memory records the last time CO was detected or the unit was tested.
It is the simplest dependable CO alarm for most homes.
First Alert Plug in Carbon Monoxide Alarm with Digital Display CO615
2The First Alert CO615 adds a digital display and a peak level feature that shows the highest CO concentration measured.
👍 Pros & Cons
Pros
- Digital display
- Peak level shows highest CO measured
- 7-year limited warranty
Cons
- Takes an outlet
📄 Detailed Review
- Type: Plug-in CO alarm, digital
- Includes: Alarm + backup battery
- Key feature: Digital display, peak level, battery backup
It plugs into an outlet with battery backup and sounds an 85 dB alarm.
It is our pick for a digital readout.
Kidde Carbon Monoxide Detector, 10-Year Battery, Digital Display, 3rd Edition
3Kidde’s 10-year CO detector runs on a sealed lithium battery, so you never change batteries.
👍 Pros & Cons
Pros
- 10-year battery, no battery swaps
- Digital display
- Wall or tabletop
Cons
- Whole unit is replaced at end of life
📄 Detailed Review
- Type: Battery CO alarm, digital
- Includes: Alarm
- Key feature: Sealed 10-year lithium battery, display updates every 15 s
Its digital display updates every 15 seconds, and three LEDs show normal, alarm and replace status.
It is our pick for no-hassle protection.
Check Kidde 10-Year Battery CO Detector, Digital Price on Amazon
First Alert Battery Carbon Monoxide Alarm CO400
4The First Alert CO400 is a battery-powered CO alarm with an electrochemical sensor and an 85 dB siren.
👍 Pros & Cons
Pros
- Battery-powered, works in outages
- End-of-life chirp
- 5-year limited warranty
Cons
- No digital readout
📄 Detailed Review
- Type: Battery CO alarm
- Includes: Alarm + batteries
- Key feature: Electrochemical sensor, 85 dB
An end-of-life chirp tells you when to replace it, and it carries a 5-year limited warranty.
It is a budget favorite.
Kidde Smoke & Carbon Monoxide Detector, 10-Year Battery, 30CUD10
5The Kidde 30CUD10 detects both smoke and carbon monoxide and runs on a built-in 10-year battery.
👍 Pros & Cons
Pros
- Smoke and CO in one
- 10-year battery
- Helps reduce cooking false alarms (maker claim)
Cons
- Replace the whole unit at end of life
📄 Detailed Review
- Type: Smoke and CO combo
- Includes: Alarm
- Key feature: 10-year battery, UL 217 and UL 2034
Kidde says it is tested to UL 217 and UL 2034 and helps reduce cooking false alarms.
It is our pick for a combo alarm.
Kidde Smart CO Detector + Indoor Air Quality, Plug-in & AA Battery, COPDLQW
6Kidde’s smart CO detector sends phone alerts through the Kidde app and also tracks humidity and TVOC levels.
👍 Pros & Cons
Pros
- Phone alerts with no subscription (maker claim)
- Low-level CO alerts from 30–70 ppm
- Tracks humidity and TVOC
Cons
- 2.4 GHz Wi-Fi only
📄 Detailed Review
- Type: Smart plug-in CO alarm
- Includes: Alarm + 2 AA batteries
- Key feature: Wi-Fi alerts, low-level CO, IAQ
It gives earlier low-level CO alerts at 30–70 ppm and a separate alarm pattern at 70 ppm.
It suits families who want alerts away from home.
X-Sense Wireless Combination Smoke and CO Detector, XP0H-WN, 3-Pack
7The X-Sense XP0H-WN 3-pack interconnects wirelessly, so when one alarm detects smoke or CO, all of them sound.
👍 Pros & Cons
Pros
- All alarms sound together
- 10-year sealed batteries
- No wiring needed
Cons
- No Wi-Fi app
📄 Detailed Review
- Type: Interconnected smoke and CO
- Includes: 3 alarms
- Key feature: Wireless interconnect, 10-year batteries
Each alarm runs on a sealed 10-year battery.
It is our pick for whole-home coverage without wiring.
Kidde Carbon Monoxide + Explosive Gas Alarm, Plug-in with 9V Battery Backup, Digital Display
8This Kidde alarm detects carbon monoxide plus explosive gases such as natural gas and propane.
👍 Pros & Cons
Pros
- Detects CO and explosive gas
- Digital display shows CO or GAS
- 9V backup
Cons
- Placement rules differ for gas
📄 Detailed Review
- Type: Plug-in CO and gas alarm
- Includes: Alarm + 9V battery
- Key feature: Detects CO plus natural gas and propane
Its display shows the CO level or reads GAS when explosive gas is present.
It suits homes with gas appliances.
How We Chose the Best Carbon Monoxide Detector
To choose the best carbon monoxide detector, we compared popular CO alarms and smoke-and-CO combos on Amazon by power source, display, alerts, listed standards and owner feedback.
CDC advises installing battery-operated or battery back-up CO detectors near every sleeping area; see the CDC carbon monoxide poisoning basics.
Product details in this guide are based on manufacturer specifications and verified owner feedback. Read more on our How We Test page.
Buying Guide: Choosing a CO Detector
Keep these points in mind before you buy.
Plug-in, battery or hardwired
Plug-in alarms need an outlet and a backup battery; battery alarms go anywhere; hardwired alarms suit homes with existing wiring. CDC recommends battery-operated or battery back-up detectors.
Where to install CO alarms
CDC advises a detector near every sleeping area. Many makers also suggest one on every level; follow the manual on distance from fuel-burning appliances.
Digital display and peak level
CDC suggests considering a detector with a digital readout, which can show the highest CO level in your home in addition to sounding an alarm.
Look for UL 2034
Home CO alarms in the US are tested to UL 2034. Combo alarms also list UL 217 for smoke.
Replace on schedule
CDC says to replace a CO detector following the maker’s instructions or every 5 years. Most alarms chirp at end of life; 10-year models are replaced as a whole unit.
If the alarm sounds
Get everyone outside to fresh air right away and call 911. Do not go back inside until responders say it is safe.
CO Safety Tips
Stay protected:
- Test alarms monthly.
- Check batteries spring and fall.
- Service fuel appliances yearly.
- Never run generators indoors.
Quick answers about the best carbon monoxide detector.
Frequently Asked Questions
What is the best carbon monoxide detector?
The best carbon monoxide detector for most homes is the Kidde plug-in with AA backup, with the First Alert CO615 if you want a digital readout.
Where should I put a carbon monoxide detector?
CDC advises a detector near every sleeping area; follow the maker’s manual for exact placement.
How often should CO detectors be replaced?
CDC says follow the maker’s instructions or every 5 years.
Do I need a digital display?
It is optional; CDC notes it can show the highest CO level.
What should I do if the alarm sounds?
Get everyone outside to fresh air and call 911.
Final Verdict
Our final pick for the best carbon monoxide detector is the Kidde Plug-In CO Detector (AA Backup). Choose the First Alert CO615 Digital CO Alarm if you want a digital display, or the Kidde 10-Year Battery CO Detector, Digital with no battery changes.
Related Guides
More home safety guides:
- Best Emergency Power Supply for Home
- Best Air Purifier for Bedroom
- Best Electric Blanket for Home
- Best Refrigerator Organizer
Product details are based on manufacturer specifications at the time of writing. Prices and availability change often, so check Amazon for the latest price.
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