A noise exposure calculator answers the permissible-time question directly — — how long is this level allowed, and where does the shift stand? OSHA and NIOSH answers side-by-side. The dose-by-task view lives on the noise dose calculator and protection on ear muffs.
What does the noise exposure calculator return?
Short answer: enter a dBA level; the tool returns OSHA’s permissible duration (5-dB exchange from 90 dBA) beside NIOSH’s recommended limit (3-dB from 85 dBA) — the divergence is the story.
Editor's pick — 3M Peltor ear muffs
The over-ear answer for the levels where this calculator’s clock runs short. Read the full listing.VIEW THE LISTING → CHECK PRICE ON AMAZON →
As an Amazon Associate, WC Safety earns from qualifying purchases. This has no bearing on which products appear here or in what order.
Enter a noise level and exposure time to get your daily noise dose under both OSHA's PEL (90 dBA criterion, 5-dB exchange rate) and NIOSH's REL (85 dBA criterion, 3-dB exchange rate), plus the maximum allowed duration at that level and what an earplug or muff's NRR actually delivers after field derating.
How the math works
Both limits allow 8 hours at their criterion level and halve (or double) the allowed time with each exchange-rate step. OSHA's permissible exposure limit uses 90 dBA with a 5-dB exchange: 8 h at 90, 4 h at 95, 2 h at 100. NIOSH's recommended limit uses 85 dBA with a 3-dB exchange — the physics-honest doubling rate — so: 8 h at 85, 4 h at 88, 2 h at 91. Dose is time-at-level divided by allowed-time, expressed as a percentage; 100% is the limit. OSHA separately sets an action level at 85 dBA (8-hour TWA) that triggers a hearing conservation program under 29 CFR 1910.95.
Common levels to try
Typical values from our decibel levels chart: circular saw ~100–105 dBA, angle grinder ~95–105, chainsaw ~105–115, impact wrench ~100, shop vacuum ~85–95, tractor cab ~85–95, concert ~100–110. At 100 dBA, OSHA allows 2 hours unprotected; NIOSH allows 15 minutes.
Picking protection once the number says you need it
Match the derated NRR to your overexposure, then pick a format workers will actually wear all shift: earplugs (see best foam earplugs and disposable picks), ear muffs (construction picks), or electronic muffs that pass speech and range commands. The full range lives in the hearing protection collection, and when do you need hearing protection walks the decision from scratch.
This calculator provides general guidance using the published OSHA PEL and NIOSH REL formulas — it is not a compliance determination, dosimetry, or medical advice. Workplace programs need measured TWA data and a qualified professional. WC Safety participates in the Amazon Associates Program; product links on this site may earn us a commission.
Our methodology
The calculator implements both the OSHA permissible-exposure table and the NIOSH recommended exposure limit so the regulatory floor and the health-based ceiling sit side by side. Authoritative duties live at OSHA regulations and exposure science at NIOSH. We hold no safety certification, and this tool is not a substitute for professional judgment.
Why trust this page
WC Safety is an independent review site with no products of its own — nothing here is stocked, warehoused or shipped by us. Purchase links go to Amazon and earn an affiliate commission at no extra cost to you. This free tool is informational — it supports, and never replaces, a written program, a hazard assessment, or evaluation by a qualified safety professional.
Frequently Asked Questions
Why do OSHA and NIOSH disagree?
Different mandates — OSHA sets an enforceable floor with a 5-dB exchange; NIOSH recommends from hearing-loss data with 3-dB. At 100 dBA that is 2 hours vs 15 minutes.
Which number should my program use?
Complying with OSHA while designing to NIOSH is the defensible posture — the law is the minimum, not the goal.
How accurate are phone sound meters?
Good enough to screen, not to certify — calibrated meters and dosimeters carry the program. Treat phone readings as a reason to measure.
Does hearing protection extend allowed time?
Effectively yes — derated attenuation lowers the at-ear level. The NRR calculator on this site does that math honestly.
What about impulse noise?
Peaks above 140 dB are never permitted unprotected — gunfire and powder-actuated tools live there. Peak limits ride alongside the duration table.
Is one loud day damaging?
It can be — noise injury is cumulative AND acute. Ringing ears after a shift is damage reporting itself.
Researched and written by Steven Eaton, editor of WC Safety. Steven holds no safety certification and does not test products; this page compares what manufacturers publish, with the gaps in that record marked. Last reviewed July 2026.