Best Carbon Monoxide Detectors in 2026

For 2026 we prioritized UL-listed CO sensing above everything, because a carbon monoxide alarm is a life-safety device before it is a smart gadget. On top of that we weighed real-time phone alerts with room-level location, ecosystem fit across Amazon Alexa, Google Home, Apple HomeKit, and Matter, whether a hub is required, local control for reliability when the internet drops, sensor lifespan, and whether any monthly fee applies. Combination smoke-and-CO units earn bonus points for consolidating two alarms into one. You can also browse all smart home devices.

Place CO detectors on every level of the home and near sleeping areas, following your local code. Prefer UL-listed units, and choose a combination smoke/CO alarm if you want fewer devices to buy and maintain. If you are on HomeKit or Alexa, confirm ecosystem support and whether a hub is needed before buying. Hardwired and interconnected models are the most reliable because they alert every room at once, but they need an electrician; battery models are renter-friendly. CO sensors expire, typically after seven to ten years, and must be replaced on schedule. See also the best smart smoke detectors in 2026.

For a connected home, a smart combination alarm like the First Alert Onelink Safe & Sound or Google Nest Protect gives you room-level alerts and voice warnings with no monthly fee. On a budget, a UL-listed X-Sense or Kidde combo covers the essentials for far less, and a simple First Alert battery CO alarm is a smart, cheap supplement for a spare room or rental.