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NIOSH noise dose calculator

Enter a dBA level and how long you were exposed. See your daily noise dose against the NIOSH (8h at 85 dBA, 3 dB exchange) and OSHA (8h at 90 dBA, 5 dB exchange) permissible exposure limits.

Educational tool, not a workplace dosimeter. Real occupational noise assessment uses a calibrated body-worn dosimeter and complies with regional regulations. Use this calculator to build intuition, not to justify exposure decisions.

Add your exposures

Add as many exposure rows as your day has. The dose is summed across all rows. NIOSH dose is the more conservative number, with a 3 dB exchange rate (every +3 dB halves the allowed exposure time).

Source label Level (dBA) Duration

Daily dose

NIOSH (3 dB exchange, REL 85 dBA / 8h)

— %

OSHA (5 dB exchange, PEL 90 dBA / 8h)

— %

Quick reference: time to 100% NIOSH dose

85 dBA: 8 hours

88 dBA: 4 hours

91 dBA: 2 hours

94 dBA: 1 hour

97 dBA: 30 minutes

100 dBA: 15 minutes

103 dBA: 7.5 minutes

106 dBA: 3 min 45 s

109 dBA: 1 min 53 s

112 dBA: 56 seconds

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The NIOSH formula

NIOSH's recommended exposure limit (REL) is 85 dBA averaged over 8 hours, with a 3 dB exchange rate. The exchange rate means that for every 3 dB increase in level, the safe daily exposure time halves. The percent-of-daily-dose for a single exposure of duration T hours at level L dBA is:

D_NIOSH = 100 × T / (8 × 2^((85 − L) / 3))

OSHA uses 90 dBA / 8h with a 5 dB exchange rate, which is more permissive than NIOSH. The same formula with the OSHA constants:

D_OSHA = 100 × T / (8 × 2^((90 − L) / 5))

For multiple exposures across a day, the doses are added. A combined dose above 100% means the exposure exceeded the permissible limit for that standard.

Why NIOSH is more conservative than OSHA

OSHA's permissible exposure limit (PEL) is the regulatory floor in US workplaces. It is older. NIOSH's REL is what hearing-conservation science currently recommends, and it accounts for the fact that the dose-response curve for noise damage is steeper than OSHA's 5 dB exchange rate assumes. The 3 dB exchange matches the underlying physics: doubling the energy of a sound increases its level by 3 dB.

Most modern hearing-conservation programs target NIOSH compliance, not just OSHA, because NIOSH-compliant exposure is closer to actually preventing noise-induced hearing loss.

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