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Noise Exposure Dose Calculator

Reviewed by the CalculatorHub team, edited by James Graham. OSHA 29 CFR 1910.95 formula. Last verified 15 June 2026.

OSHA's noise exposure standard (29 CFR 1910.95) uses a dose approach to evaluate whether workers are overexposed across a shift with varying noise levels. The dose percentage D = (C/T) x 100, where C is the actual time exposed and T is the permissible time at that level from OSHA's table. A dose of 100% equals the permissible exposure limit (90 dBA TWA for 8 hours). At 50% dose (85 dBA TWA), an employer must implement a Hearing Conservation Program. Enter the average noise level in dBA and the hours of exposure.

Time-averaged A-weighted sound level (OSHA range: 90-115 dBA)
Hours actually spent at this noise level per shift
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OSHA dose formula

T = 8 / 2(L-90)/5
Dose (%) = (C / T) × 100

Where L is the noise level in dBA, C is actual exposure in hours, and T is the permissible exposure time from OSHA's table. The 5 dB exchange rate means each 5 dB increase halves the allowable time.

OSHA permissible exposure times

  • 90 dBA: 8 hours (PEL for 8-hr shift)
  • 95 dBA: 4 hours
  • 100 dBA: 2 hours
  • 105 dBA: 1 hour
  • 110 dBA: 0.5 hours (30 minutes)
  • 115 dBA: 0.25 hours (15 minutes, maximum)

Frequently asked questions

What is the OSHA noise exposure limit?

OSHA's permissible exposure limit (PEL) is 90 dBA for an 8-hour workday. Each 5 dB increase halves the permissible exposure time (the exchange rate is 5 dB). A 100% dose means the PEL has been reached.

What is the noise dose formula?

Dose (%) = (C/T) x 100, where C is the actual exposure time in hours and T is the permissible time at that level. For multiple noise levels: D = (C1/T1 + C2/T2 + ...) x 100.

What is the permissible exposure time at different levels?

OSHA's table: 90 dBA = 8 hrs; 95 dBA = 4 hrs; 100 dBA = 2 hrs; 105 dBA = 1 hr; 110 dBA = 0.5 hrs; 115 dBA = 0.25 hrs. The formula is T = 8 / 2^((L-90)/5) for L between 90 and 115 dBA.

What dose percentage triggers action?

OSHA requires a Hearing Conservation Program when the action level (50% dose, or TWA of 85 dBA) is reached. A dose of 100% or more violates the PEL and engineering controls or hearing protection are required.

Does NIOSH use a different standard?

Yes. NIOSH recommends a more protective 85 dBA PEL for 8 hours and a 3 dB exchange rate (halving time). This calculator implements the OSHA standard (90 dBA PEL, 5 dB exchange rate) as it is the US legal standard.

Official sources

Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.