How loud is an impact wrench?
DeWALT declares 97 dB(A) for its DCF921 and DCF922 cordless impact wrenches and 96 dB(A) for the DCF923, A-weighted emission sound pressure at the operator in the standard test, with sound power of 107 to 108 dB(A). The US Federal Transit Administration lists a typical impact wrench at 85 dBA at 50 ft.
- Level
- 96–97 dBAA-weighted sound level
- Daily limit
- 30 min a dayNIOSH, at the loud end
- Versus conversation
- 2,512× energyabout 10.6× as loud
What the numbers mean
How it was measured. DeWALT-declared emission sound pressure levels (LpA) for its DCF921, DCF922 and DCF923 18 V cordless impact wrenches, tested to EN 62841-2-2.
An impact wrench uses a hammering mechanism to free or tighten nuts, and its declared level is several dB higher than the DeWALT cordless drills and grinders listed elsewhere on this site. The sound power level, the total noise radiated, is 108 dB(A) for the DCF921 and DCF922 and 107 dB(A) for the DCF923.
For people nearby, the FTA construction equipment table reproduced in the FHWA Construction Noise Handbook gives a typical impact wrench level of 85 dBA at 50 ft (about 15 m).
How long is safe?
NIOSH recommends no more than 30 min a day at 97 dBA (38 min at 96). OSHA's legal limit is 3 h 2 min.
| 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 |
|---|---|---|---|---|
| 96 dBA | 38 min | 3 h 29 min | 12 min | 38 min |
| 97 dBA | 30 min | 3 h 2 min | 9 min 35 s | 30 min |
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.
Protecting your hearing
Wear plugs or muffs when using an impact wrench for more than a few nuts, for example a set of wheel changes. Pneumatic workshop wrenches add compressed-air exhaust noise on top.
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).
- Angle grinder (83–104.7 dBA): this has about 1.8× its sound energy and sounds about 1.2× as loud.
- Symphony orchestra (86–102 dBA): this has about 1.8× its sound energy and sounds about 1.2× as loud.
- Music festival (95.8–101.4 dBA): it has about 1.6× the sound energy of this and sounds about 1.2× as loud.
- Circular saw (89–110.4 dBA): it has about 2.1× the sound energy of this and sounds about 1.2× as loud.
- Normal conversation (55–70 dBA): this has about 2,512× its energy and sounds about 10.6× as loud.
Questions
How loud is a cordless impact wrench?
DeWALT declares 96 to 97 dB(A) at the operator for its 18 V DCF921/922/923 impact wrenches.
How loud is an impact wrench from across a workshop or street?
A planning table from the US Federal Transit Administration gives 85 dBA at 50 ft (15 m) as typical.
Sources
- DeWALT DCF921/DCF922/DCF923 18 V cordless impact wrench instruction manual, DeWALT (manufacturer). Supports: dB_low/high: LpA 97, 97, 96 dB(A).
dB(A) 97 97 96
Checked 2026-11-03. - DeWALT DCF921/DCF922/DCF923 18 V cordless impact wrench instruction manual, DeWALT (manufacturer). Supports: body: LWA 107-108 dB(A).
LWA (sound power level) dB(A) 108 108 107
Checked 2026-11-03. - Construction Noise Handbook, 9.0 Construction Equipment Noise Levels and Ranges, Federal Highway Administration (US Department of Transportation). Supports: body: 85 dBA typical at 50 ft.
Impact Wrench 85
Checked 2026-11-03.
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.