How loud is a smoke alarm?
A smoke alarm is about 85 dB, with a typical range of 85–95 dB. Alarms must reach at least 85 dB at 3 m (10 ft).
That is about 6 times as loud to the ear as normal conversation and 316 times the sound energy.
Can it damage your hearing?
Yes, with enough exposure. At 85 dBA, NIOSH recommends a daily limit of 8.0 hours; at the top of the range (95 dB) it is 48 minutes. Wear earplugs or earmuffs, keep your distance and limit time near the source.
How sound level changes with distance
Decibel figures always depend on distance. For a small source in open air, every doubling of distance lowers the level by about 6 dB; indoors, reflections reduce that drop. Use the sound-vs-distance calculator to estimate the level where you are.
Sounds as loud as a smoke alarm
Cruising flight; seats near the engines are louder.80 dBAlarm clock
Measured at the pillow.80 dBGarbage disposal
Kitchen sink food waste disposer.85 dBGas lawn mower
CDC lists gas mowers and leaf blowers at 80–85 dB; operator-ear levels can be higher.85 dBHair dryer
Very close to the ear while in use.85 dBHeavy city traffic
Standing at the curb of a busy street.85 dBMovie theater
CDC gives 74–104 dB depending on the film and seat.88 dBBlender
High-power blenders crushing ice are the loudest.
Safe listening time
| Level | NIOSH recommended limit | OSHA legal limit (US) |
|---|---|---|
| 79 dBA | 32.0 hours | 36.8 hours |
| 82 dBA | 16.0 hours | 24.3 hours |
| 85 dBA | 8.0 hours | 16.0 hours |
| 88 dBA | 4.0 hours | 10.6 hours |
| 91 dBA | 2.0 hours | 7.0 hours |
NIOSH: 85 dBA for 8 hours with a 3 dB exchange rate; OSHA: 90 dBA for 8 hours with a 5 dB exchange rate. General information, not medical advice – see a hearing professional about ringing ears, muffled hearing or pain.
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Frequently asked questions
How many decibels is a smoke alarm?
About 85 dB, with a typical range of 85–95 dB.
Is a smoke alarm louder than a jet engine?
No – a jet engine at takeoff is about 140 dB at 30 m, while a smoke alarm is about 85 dB.
How are these levels measured?
With a sound level meter, usually A-weighted (dBA) to match human hearing. Published figures depend on distance and conditions, so treat them as typical values.