How often should you test smoke detectors?

Test every detector once a month: press the button, hear the alarm, done. Replace the batteries once a year. Replace the detectors themselves every ten years.

That third interval surprises people, so let’s start there.

Detectors expire

The sensor inside a smoke detector degrades with age, whether or not it has ever sounded, whether or not the test button still works. After about ten years it can no longer be trusted to detect smoke reliably, and every manufacturer and fire-safety agency says the same thing: replace the unit.

Most homes have no idea how old their detectors are. Take a screwdriver, pull each one down, and look at the manufacture date printed on the back. If it’s more than ten years old, or there’s no date at all, replace it today. This is the highest-value ten minutes in this entire guide.

The monthly button press

The test button confirms the battery, the horn, and the circuit. Once a month, press and hold until the alarm sounds, for every detector in the house. If you have small children, consider doing it while they’re awake and expecting it; a surprise test at nap time helps no one, and kids who recognize the sound are safer for it.

Twice a year, give each unit a pass with the vacuum’s brush attachment. Dust and cobwebs in the sensor chamber are a leading cause of both missed alarms and the false 3 a.m. chirps that tempt people into pulling batteries. Never leave a detector without a working battery, even overnight. Most home fire deaths happen where there is no working smoke alarm, and a unit with its battery on the counter counts as one.

Batteries: yearly, or not at all

If your detectors take replaceable batteries, change them once a year, every unit, same day. Pick a date you can’t forget; plenty of fire departments suggest the day you change the clocks.

If your detectors have sealed ten-year lithium batteries, you’re excused from this one entirely. No yearly swap, no chirps at 3 a.m. The unit and its battery retire together at the ten-year mark. When your current detectors age out, sealed units are worth the upgrade for that reason alone.

If your detectors are interconnected

In many newer homes the detectors are wired together: one alarm triggers them all, so a fire in the basement wakes the second floor. If yours work this way, test the link twice a year. Press and hold the test button on one unit and confirm every other alarm in the house answers. A broken interconnection is invisible in the monthly single-unit test, and the whole point of the system is the units you’re not standing next to.

The schedule, all together

• Press the test button on every unit: monthly
• Vacuum each unit: every six months
• Test the interconnection, if you have it: every six months
• Replace batteries: yearly (skip if sealed ten-year units)
• Replace every detector: ten years from its manufacture date

Nothing on this list takes real effort. It only takes remembering, on schedule, for years. That part doesn’t have to live in your head.