How loud is a smoke alarm? 85 dB

What the numbers mean

How it was measured. Rated alarm output stated by two manufacturers of UL 217 certified alarms; weighting not stated in the sources (the figure is commonly given as dBA).

Smoke alarms are built to one loudness target. First Alert's SM210 specification sheet lists 'Audio Alarm: 85dB at 10 feet' for an alarm certified to UL 217, the US standard for smoke alarms, and Kidde says all its alarms sound at about 3,000 Hz and 85 decibels at 10 feet.

A 3 kHz tone sits where human hearing is very sensitive, so it sounds piercing. Because sound drops as you move away, the level right under a ceiling alarm when you press the test button is higher than the rated figure at 10 feet.

Loudness alone is not the whole answer. Researchers writing in Injury Epidemiology (2020) note that the high-frequency tone smoke alarms in many homes will not adequately awaken children who are old enough to self-rescue, and have tested alternative alarm signals that do.

How long is safe?

NIOSH recommends no more than 8 h a day at 85 dBA. OSHA's legal limit is not reached below 90 dBA. This level is not A-weighted, so the times are approximate: low-pitched sound measures lower in dBA.

Level	NIOSH limit (85 dBA, 3 dB rule)	OSHA limit (90 dBA, 5 dB rule)	UK/EU 80 dB(A) action value reached after	UK/EU 85 dB(A) action value reached after
85 dB	8 h	No limit	2 h 32 min	Not reached in 24 h

Times are for a whole day’s exposure, with the rest of the day quiet. The workplace limits were written for adults at work, not for children. Work out a mixed day with the noise dose calculator.

Children

Children can sleep through high-pitched smoke alarms. Plan and practise a fire escape route with them rather than assuming the alarm will wake them.

Pets

The test beep is very loud for dogs and cats. Keep them out of the room when you test alarms.

Protecting your hearing

When testing, press the button with your arm extended and turn your head away, or cover the ear nearest the alarm. Test for a second or two, not continuously.

Earplug and earmuff ratings (NRR in the US, SNR in the UK and EU) are lab figures; real-world protection is usually lower. How to read the ratings.

Compared with sounds nearby

Using midpoints of each range. Energy multiplies by 10 every 10 dB; perceived loudness roughly doubles (why).

Quiet library (40–44 dB): this has about 19,953× its sound energy and sounds about 19.7× as loud.
Ocean waves (60–78 dB): this has about 40× its sound energy and sounds about 3.0× as loud.
Birdsong (74–103 dB max): it has about 2.2× the sound energy of this and sounds about 1.3× as loud.
Sonic boom (75–110 dB max): it has about 5.6× the sound energy of this and sounds about 1.7× as loud.

Questions

How many decibels is a smoke alarm?

85 dB at 10 feet (3 m), as quoted by First Alert and Kidde for their UL 217 certified alarms.

Can a smoke alarm damage your hearing?

A short test is unlikely to, but the level close to the alarm is higher than the rated 85 dB at 10 feet, so keep your ear away from it when testing.

Sources

SM210 Spec Sheet, First Alert (BRK Brands / Resideo). Supports: dB_low/dB_high: 85 dB at 10 ft.Audio Alarm: 85dB at 10 feetChecked 2026-11-02.
SM210 Spec Sheet, First Alert (BRK Brands / Resideo). Supports: UL 217 certification.Listing: Certified to UL217Checked 2026-11-02.
Alarm frequency, Kidde. Supports: 85 dB at 10 ft; 3,000 Hz tone.At 10 feet, the sound is 85 decibels.Checked 2026-11-02.
Optimizing smoke alarm signals: Testing the effectiveness of children's smoke alarms for sleeping adults, Injury Epidemiology. Supports: context: children and high-frequency alarms.the high-frequency tone smoke alarms in many homes will not adequately awaken children who are old enough to self-rescueChecked 2026-11-02.

This page is general information, not medical advice. If you have ringing in your ears, muffled hearing or any change in your hearing, see an audiologist or your doctor.