Noise Exposure Calculator
Add up daily noise exposure across tasks to get the dose %, 8-hour TWA and permissible exposure time, on the OSHA (90 dB / 5 dB) or NIOSH (85 dB / 3 dB) standard. Fully offline.
Open Noise Exposure Calculator →What is the noise exposure calculator?
A free, private calculator that adds up daily occupational noise exposure across separate tasks. It works out the total noise dose as a percentage, the 8-hour time-weighted average (TWA), and each task's permissible exposure time, on either the OSHA (90 dB / 5 dB) or NIOSH (85 dB / 3 dB) standard. It calculates live as you type, saves on your device, and runs fully offline in your browser.
How to use Noise Exposure Calculator
- Pick a standard — Choose OSHA (90 dB criterion, 5 dB exchange) or NIOSH (85 dB criterion, 3 dB exchange) from the dropdown.
- Add your tasks — Use + Add task for each noise source, naming it so you can tell the rows apart.
- Enter level and hours — For each task, type the sound level in dBA and the number of hours the worker is exposed to it.
- Read the results — Each row shows its permissible time and partial dose, while the cards give the total daily dose and the 8-hour TWA.
Frequently asked questions
What does a 100% dose mean?
A dose of 100% equals the standard's full permissible daily exposure. Above 100% means the day exceeds the limit; the dose figure is colour-coded as within limits, approaching the limit, or over it.
What's the difference between OSHA and NIOSH?
OSHA uses a 90 dB reference level and a 5 dB exchange rate, while NIOSH uses a stricter 85 dB level and a 3 dB exchange rate. The same tasks usually give a higher dose under NIOSH.
What is the 8-hour TWA?
The time-weighted average is the steady noise level that would produce the same total dose over an 8-hour shift, expressed in dBA.
Is my data uploaded anywhere?
No. Everything is calculated and saved entirely in your browser, so your task data stays on your device and the tool works offline.
Can I model a day made of several different jobs?
Yes. Add a row per task with its own level and hours, and the calculator combines the partial doses into one total for the day.
Tips
- Break a shift into separate tasks so loud, short jobs are weighted correctly against quieter ones.
- Switch standards to compare your figures against both the OSHA and the stricter NIOSH limits.
- Watch the permissible time column — it tells you how long a worker can stay at each level before reaching the dose limit.