Audio calculator
Noise Exposure Calculator (NIOSH / OSHA)
Under the NIOSH recommended limit, allowed exposure halves for every 3 dB above 85 dBA: eight hours at 85, one hour at 94, fifteen minutes at 100. Enter the levels and durations of your day and this calculator returns the noise dose under both the NIOSH and OSHA formulas.
Screening math only, using published NIOSH/OSHA exposure formulas. Hearing conservation compliance is measured with dosimetry by qualified people, not a web calculator.
Formulas
Allowed time at a level
T = 8 hours / 2^((L - criterion) / exchange)- L:
- exposure level in dBA
- criterion:
- 85 dBA (NIOSH) or 90 dBA (OSHA)
- exchange:
- 3 dB (NIOSH) or 5 dB (OSHA)
Daily dose
dose% = 100 × Σ (Ci / Ti)- Ci:
- time actually spent at each level
- Ti:
- allowed time at that level
How it works
Hearing damage tracks total acoustic energy, so the standards trade level against time. NIOSH (the research institute) recommends the stricter version: 85 dBA for 8 hours with a 3 dB exchange rate, matching the physics of energy doubling. OSHA (the regulator) permits 90 dBA with a 5 dB exchange, a legal limit rather than a safe-harbor recommendation.
The difference compounds fast. At 100 dBA, a loud but unremarkable FOH level, NIOSH allows 15 minutes and OSHA allows 2 hours. A festival crew working a 10-hour day near the PA can exceed a NIOSH dose before the headliner starts, which is why dosimeter badges and rotated positions exist on serious productions.
The mix position is quieter than the barricade but not safe by default: show levels of 96 to 102 dBA at FOH are routine. Musician earplugs with flat attenuation take 10 to 25 dB off every number in this calculator, which converts most over-limit days into legal ones. Crews who protect their ears stay employable; the ones who do not retire into a permanent ring.
Worked example: Festival stagehand: 2 hours at 96 dBA during shows, 4 hours at 85 dBA otherwise
- 1.NIOSH allowed at 96 dBA: 480 / 2^((96-85)/3) = 480 / 12.7 = 37.8 minutes.
- 2.Dose from the loud segment: 120 / 37.8 = 317%.
- 3.Dose from the quiet segment: 240 / 480 = 50%. Total: 367% of a NIOSH day. Under the OSHA PEL calculation, the 85 dBA segment is below the 90 dBA threshold, so the total is 57%.
More than triple the NIOSH dose. Earplugs during shows bring it under 100%.
Allowed daily exposure by level
| Level | NIOSH (85/3) | OSHA (90/5) |
|---|---|---|
| 85 dBA | 8 h | Below PEL threshold |
| 91 dBA | 2 h | 7 h |
| 94 dBA | 1 h | 4.6 h |
| 97 dBA | 30 min | 3 h |
| 100 dBA | 15 min | 2 h |
| 103 dBA | 7.5 min | 1.3 h |
| 106 dBA | 3.75 min | 52 min |
Field notes
- A-weighted, slow-averaged measurements are what the formulas expect; phone SPL apps vary but are close enough for screening.
- This OSHA PEL result uses OSHA’s 90 dBA measurement threshold. OSHA hearing-conservation measurements use an 80 dBA threshold and answer a different compliance question.
- The exchange-rate difference means quiet breaks matter enormously under NIOSH math: lunch away from the PA is a hearing-conservation tool.
Frequently asked questions
How long can I safely be exposed to 100 dB?
NIOSH allows about 15 minutes per day at 100 dBA; OSHA permits 2 hours. Every 3 dB louder halves the NIOSH time. Earplugs extend all of these numbers by their rated attenuation.
What is the difference between NIOSH and OSHA noise limits?
OSHA sets the enforceable legal limit for US workplaces: 90 dBA over 8 hours with a 5 dB exchange rate. NIOSH publishes the health-based recommendation: 85 dBA with a 3 dB exchange. NIOSH reflects the injury data; OSHA is what citations are written against.
How loud is a concert at front of house?
Typical rock and EDM shows run 96 to 103 dBA averaged at the mix position, with peaks well above. Many festivals and some jurisdictions cap show level at a measured limit (often 100 to 102 dBA over a rolling average) at FOH.