Noise exposure calculator
Safe exposure calculator
How long a level is safe, using the NIOSH (85 dB/3 dB) and OSHA (90 dB/5 dB) rules.
NIOSH vs OSHA safe times
| Level | NIOSH (85/3 dB) | OSHA PEL (90/5 dB) |
|---|---|---|
| 85 dBA | 8 hours | 16 hours |
| 88 dBA | 4 hours | 11 hours |
| 90 dBA | 2.5 hours | 8 hours |
| 91 dBA | 2 hours | 7 hours |
| 94 dBA | 1 hour | 4.6 hours |
| 97 dBA | 30 min | 3 hours |
| 100 dBA | 15 min | 2 hours |
| 103 dBA | 7.5 min | 1.3 hour |
| 106 dBA | 3.8 min | 52 min |
| 110 dBA | 1.5 min | 30 min |
| 115 dBA | 28 sec | 15 min |
| 120 dBA | 8.9 sec | 7.5 min |
The two standards differ by design. NIOSH is the health-based recommendation and uses a strict 3 dB exchange rate — the physically correct one, since 3 dB doubles energy. OSHA’s legal permissible limit uses a more lenient 5 dB exchange rate. Where they disagree, the NIOSH figure is the safer target.
What the daily dose means
Exposure is cumulative. Two hours at 91 dBA uses your entire daily NIOSH allowance; add any more loud noise and you are over. This is why a single loud concert or afternoon with power tools can matter, and why hearing protection — which effectively lowers the level reaching your ear — buys back so much safe time.
Hearing protection
For anything above 85 dB, rated protection matters. Look at the NRR (US) or SNR (EU) figure — real-world reduction is roughly (NRR − 7) ÷ 2.
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