How this industrial noise exposure calculator works
When a shift is split across several noisy tasks, looking at the loudest level alone does not answer the question. This page takes up to three pairs of sound level and actual exposure time, works out the allowed time for each level, and adds the partial doses into a daily total. Switching the exchange rate recalculates the same inputs straight away.
The formula applied is allowed time T = 8 / 2 ^ ((measured level - base level) / exchange rate), and the daily dose is the sum of exposure time divided by allowed time for each task. The 5 dB rate anchors 90 dBA to 8 hours; the 3 dB rate anchors a recommended 85 dBA to 8 hours. These come from the systems used by the US occupational safety administration and the US occupational safety research institute, taken from secondary sources, so checking the originals is advised. Figures reflect October 2026.
Levels stay in dBA and times in hours because the published anchors are given that way. Environmental noise limit checks, background noise correction and combining several sources into one level are not covered. This calculator is for reference and does not replace design. Review by a qualified engineer is required.
Frequently asked questions
The exchange rate sets how much the sound level has to rise before the allowed time halves. The 5 dB system anchors 90 dBA to 8 hours, and the 3 dB system anchors a recommended 85 dBA to 8 hours. The allowed time differs sharply for the same level, so the two must never be mixed.
It does not state a legal limit. It shows the calculated result for the two widely used exchange rates side by side so you can see both, and you should check the standard you work to for any formal judgment.
For each task the actual exposure time is divided by the allowed time at that level, and the partial doses are added. A total above 100% means the daily allowance for that exchange rate has been passed.