How often to test and replace smoke and CO (carbon monoxide) alarms
An alarm that’s silent when it matters looks exactly like one that works. There are three separate jobs here — testing, batteries and replacing the whole alarm — and each has its own schedule.
Short answer
Test every alarm once a month by holding the test button. Change batteries once a year, unless the alarm has a sealed 10-year battery. Replace smoke alarms 10 years after the manufacture date printed on the back. Replace CO alarms when their printed end-of-life date arrives, which is often 5–7 years and is shorter than smoke alarms. An alarm past its date should be replaced even if the test button still makes it beep.
Get Gable Reminders for your house, no account, nothing leaves your phone.
Why this is worth a minute a month
US fire data consistently finds that roughly three in five home fire deaths happen in homes with no smoke alarm or no working one. The common reasons are a battery pulled out during a 3 a.m. chirp and never replaced, a dead battery, or an alarm that was simply too old.
The three schedules at a glance
| Job | How often | Notes |
|---|---|---|
| Test every smoke and CO alarm | Monthly | Press and hold the test button until it sounds |
| Replace batteries | Yearly | Not needed for sealed 10-year battery alarms. Pick one fixed date, such as when the clocks change |
| Replace smoke alarms | 10 years after the manufacture date | Sensors degrade even when the horn still works |
| Replace CO alarms | At the printed end of life, often 5–7 years | Some newer models last 10 years; the label decides |
Always follow the date and instructions printed on the alarm itself. Local fire codes may add requirements.
How to test an alarm
- Tell everyone at home first. Smoke alarms are loud.
- Press and hold the test button until the alarm sounds, usually a few seconds. On interconnected alarms, every alarm in the house should sound together.
- If it doesn’t sound, change the battery and test again. If it still doesn’t sound, replace the alarm.
- While you’re up there, vacuum the vents gently to clear dust and cobwebs.
Don’t test with a candle, a lighter or car exhaust. The button checks that the alarm’s electronics and horn work. It doesn’t prove the sensor is still sensitive, which is why the replacement date matters.
How to find an alarm’s age
Twist the alarm off its mounting plate and look at the label on the back. You’ll find a manufacture date, and on many CO and newer smoke alarms a “replace by” date too. If there’s no date at all, the alarm is almost certainly more than ten years old. Replace it.
Write the install date on the new alarm with a marker. You won’t remember it in 2036.
What the chirps mean
- A single chirp about once a minute usually means a low battery. Replace it; don’t just pull it.
- A different chirp pattern, often several chirps every 30–60 seconds, is an end-of-life warning on many alarms. A new battery won’t stop it; the alarm has to be replaced.
- Chirping right after a battery change can mean the battery isn’t seated, the drawer isn’t closed, or the alarm needs resetting (hold the test button for 15–20 seconds).
Patterns vary by brand, so check the label or manual for yours.
Where alarms should be
US fire safety guidance (NFPA) calls for smoke alarms:
- inside every bedroom,
- outside each sleeping area, such as in the hallway,
- on every level of the home, basement included.
Put CO alarms outside each sleeping area and on every level if the home has anything that burns fuel: a gas furnace, water heater, stove, fireplace, or an attached garage. Keep smoke alarms away from kitchens and bathrooms, where cooking and steam cause false alarms. Interconnected alarms, where one sounds and all sound, are worth it whenever you’re replacing several at once.
If a CO alarm goes off
Treat it as real. Get everyone, pets included, out into fresh air, then call emergency services or your gas utility from outside. Don’t go back in to look for the cause. Carbon monoxide has no smell or colour, which is the whole reason the alarm exists.
Three schedules, one app
Gable keeps the monthly alarm test, the yearly battery change, and the replacement dates for smoke and CO alarms as separate jobs on your plan, with a reminder for each. No account; nothing leaves your phone.
