Safe-T-Plug

Best Carbon Monoxide Detector

What is the best carbon monoxide detector? For most homes, the best carbon monoxide detector is the Kidde Plug-in CO Detector with AA Battery Backup. A carbon monoxide detector sounds an alarm when it senses CO gas, which you can't see or smell. This Kidde CO alarm plugs into an outlet and has battery backup.

The best battery carbon monoxide detector is the First Alert 10-Year Battery CO Alarm. The best carbon monoxide detector for gas homes is the Kidde CO and Explosive Gas Alarm.

Updated

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Quick picks

Where should carbon monoxide detectors go?

NFPA says to put CO alarms outside each sleeping area, on every level of the home, and wherever local code requires, and to follow the maker's instructions for mounting. Read NFPA's carbon monoxide safety tips and CPSC's CO alarm guide.

Our picks

Best overall

Kidde Plug-in CO Detector with AA Battery Backup

Good for: bedrooms and hallways with an outlet nearby.

  • Plugs into a standard 120V outlet
  • 2 AA batteries keep it working in a power outage
  • 85-decibel alarm
  • Peak Level Memory and a Test-Hush button
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Best with a digital display

Kidde Plug-in CO Detector with 9V Backup and Digital Display

Good for: people who want to see the CO level, not just hear an alarm.

  • Digital display shows the CO level it senses
  • 9-volt battery backup
  • 85-decibel alarm
  • Peak Level Memory
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Best First Alert plug-in

First Alert CO605 Plug-in CO Detector with Battery Backup

Good for: a simple plug-in from the other big alarm brand.

  • Plug-in with battery backup
  • Electrochemical CO sensor
  • End-of-life chirp tells you when to replace it
  • 7-year limited warranty, per the listing
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Best where there's no outlet

First Alert 10-Year Battery CO Alarm with Digital Display

Good for: spots with no outlet, and skipping battery swaps.

  • Sealed 10-year lithium battery
  • Backlit display shows CO level and temperature
  • Peak Level shows the highest reading
  • 10-year limited warranty, per the listing
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Best budget pick

Kidde AA Battery CO Alarm

Good for: an extra alarm on a wall or tabletop, or taking along when you travel.

  • Runs on 2 AA batteries, no wiring
  • Mount on a wall or set on a table
  • 85-decibel alarm with LED lights
  • Listing says UL listed
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Best for homes with propane or natural gas

Kidde Plug-in CO and Explosive Gas Alarm

Good for: homes with gas appliances, furnaces or a propane tank.

  • Alarms for carbon monoxide and explosive gas (propane, natural gas, methane), per the listing
  • Display shows the CO level or reads GAS
  • 9-volt battery backup
  • 85-decibel alarm
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Is a battery or plug-in carbon monoxide detector better?

Both work. A plug-in with battery backup keeps going in an outage and never runs flat while plugged in. A 10-year battery model goes anywhere, with no outlet needed. Pick the one that fits where it's going.

Does it matter which carbon monoxide detector I buy?

Look for a listed alarm from a known brand, then pick the features you want, like a display or gas detection. CPSC's CO alarm guide covers what to look for.

How long do carbon monoxide detectors last?

They wear out. Most have an end-of-life chirp, and the maker lists the lifespan on the alarm. Replace it when it chirps or the date runs out.

Do I need a smoke and CO combo instead?

A combo alarm covers both in one unit. See our smoke detector picks, which include combo models.

How we picked

We looked at what people actually buy on Amazon, kept the products lots of buyers already use and like, and favored known safety brands. We read each maker's listing and pulled the key details you see on the cards. We haven't lab-tested these products, so we don't give scores. Details come from the product listings as of October 10, 2026, so check the listing for current sizes, fit and safety listings before you buy.