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Noise & decibel calculators

Five free tools that turn decibel theory into numbers you can use — distance loss, source addition, safe exposure time, hearing-protection maths and a live sound meter. Everything runs in your browser; nothing is uploaded.

Safe exposure calculator

How long a level is safe, using the NIOSH (85 dB/3 dB) and OSHA (90 dB/5 dB) rules.

Noise level (dBA)

Enter a level in dBA.

Distance & sound-level calculator

How much a level drops as you move away (inverse-square law, 6 dB per doubling).

Level (dB)

At distance (m)

New distance (m)

Enter a level and two distances.

Decibel addition calculator

Combine multiple noise sources. Decibels add logarithmically, not arithmetically.

dB values (comma-separated)

e.g. two 70 dB sources make 73 dB, not 140.

Hearing-protection (NRR) calculator

Estimate the real-world level at your ear with protection, using the OSHA de-rating (NRR − 7) ÷ 2.

Noise level (dBA)

Protector NRR (dB)

Enter the noise level and the NRR rating.

Measure a real noise level

Want to check an actual sound rather than calculate one? The online sound meter uses your microphone to show live, peak and average dB. For a permanent record you may want a dedicated meter:

Sound level meters

When a phone app isn’t enough, a dedicated Class 2 meter gives repeatable readings for workplace checks, noisy neighbours or hobby audio.

Class 2 digital SPL meterCalibrated, A/C weighting, data holdLink coming soon

Pocket dosimeterLogs cumulative daily exposureLink coming soon

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More reference

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Sources & accuracy. Reference levels are drawn from published data by NIOSH, OSHA, the CDC, the WHO Environmental Noise Guidelines and the American Speech-Language-Hearing Association (ASHA). Real-world readings vary with distance, room acoustics and the specific source, so treat every figure as a typical value rather than an exact constant. Last reviewed 2026-08-11.