Buy links on this page go through our /go/ redirects to the manufacturer or retailer. We earn nothing from them today; that may change. Disclosure.
Quick answer
NFPA says every smoke alarm must be replaced 10 years after its manufacturing date. Not 10 years after you installed it. Kidde says to read the date code on the label on the back of the unit. Kidde also says carbon monoxide and combination alarms should be replaced every 7 years.
Replacement alarms and batteries:
Kidde 20SD10 (10-year battery) Kidde 20SA10 (hardwired) Energizer MAX 9VHow long each alarm lasts
| Alarm type | Replace after | Source |
|---|---|---|
| Smoke alarm | 10 years from the manufacturing date | NFPA, Kidde |
| Heat alarm | 10 years | Kidde |
| Carbon monoxide or combination alarm | 7 years | Kidde |
Finding the date
- Twist the alarm off its bracket. For a hardwired alarm, turn off the breaker first.
- Look for the label on the back. Kidde says the date code is there.
- Add 10 years for a smoke alarm. If that date has passed, replace it.
How alarms tell you they're done
- Sealed 10-year models: Kidde says they chirp every 30 seconds at end of life. Kidde says its CO alarms start chirping every 30 seconds seven years after first power-up, and won't stop until powered off.
- Replaceable-battery models: NFPA says chirping that continues after a new battery means end of life.
- Failed test: NFPA says if the monthly test doesn't sound, change the battery, or replace the unit if it's over 10 years old.
Picking a replacement
NFPA says to choose an alarm listed by a nationally recognized testing lab. Either a yearly-battery model or a 10-year sealed model protects you. Kidde lists its 20SD10 as a 10-year battery model with "never change battery" among its features. NFPA recommends interconnected alarms so that when one sounds, they all sound.
How we work: replacement ages come from NFPA and Kidde. Product details come from Kidde's product page. Sources are listed below.
Questions people ask
How long do smoke detectors last?
NFPA says replace smoke alarms 10 years after the manufacturing date. Kidde says carbon monoxide and combination alarms every 7 years.
Where is the date on a smoke detector?
Kidde says to check the date code on the label on the back of the unit.
Do 10-year sealed alarms need battery changes?
No. The sealed battery isn't replaced. Kidde says sealed-battery models chirp every 30 seconds at end of life to tell you to replace the alarm.
Sources
Last checked Oct 23, 2026. If an alarm may be real, get out first. Only qualified electricians should install hardwired smoke alarms, NFPA says. Turn off the breaker before taking down a hardwired unit.
