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How Often Should You Replace Smoke Alarms?

Replace smoke alarms every 10 years, test them monthly, and do not confuse a fresh battery with a fresh smoke sensor.

Direct answer

Replace home smoke alarms every 10 years, or sooner if the alarm fails a test, is damaged, is recalled, repeatedly chirps after proper battery replacement, or has no readable manufacture date. Changing the battery does not reset the 10-year life of the smoke sensor.

manufacture date + 10 years = replace whole smoke alarm

Smoke alarm replacement timing

Under 10 years old and passes tests

Keep testing monthly

Still within normal service life

10 years from manufacture date

Replace the whole alarm

Sensors and electronics age

No readable date

Replace

You cannot verify service life

Fails test or sounds weak

Replace or service immediately

The alarm may not warn reliably

Hardwired alarm

Still replace at 10 years

Hardwired power does not renew the sensor

Alarm situation	What to do	Why
Under 10 years old and passes tests	Keep testing monthly	Still within normal service life
10 years from manufacture date	Replace the whole alarm	Sensors and electronics age
No readable date	Replace	You cannot verify service life
Fails test or sounds weak	Replace or service immediately	The alarm may not warn reliably
Hardwired alarm	Still replace at 10 years	Hardwired power does not renew the sensor

Battery life and alarm life are different

A smoke alarm can have a fresh battery and still be too old to trust. The monthly test checks whether it sounds, but the end-of-life replacement date still matters.

Check your smoke alarms

1Find the manufacture date or replace-by date on each alarm.
2Replace any alarm that is 10 years old or has no readable date.
3Test each alarm monthly using the test button.
4Replace standard batteries when required and right away when low-battery chirps occur.
5Install replacement alarms according to current placement guidance and the manufacturer's instructions.

FAQ

Do smoke alarms really expire?

Yes. Home smoke alarms have sensors and electronics that age, so the common public-safety rule is to replace the whole alarm every 10 years, even if it still sounds during a test.

How do I know how old a smoke alarm is?

Take the alarm down and look for the manufacture date or replace-by date on the back or side label. If you cannot find the date, replacement is usually the safer choice.

Does changing the battery make an old smoke alarm safe?

No. A fresh battery can power the alarm, but it does not renew an aging smoke sensor. Replace the full alarm when it reaches end of life.

Sources & method

We reviewed these references while writing this answer. Figures are estimates — confirm safety-critical work with a professional. Last updated June 7, 2026.