Can I add two 60 dB sources as 120 dB?

No. Sound levels are logarithmic. Two identical 60 dB sources combine to about 63 dB.

Does this measure noise with my microphone?

No. It calculates from values you enter. Use a calibrated sound meter or dosimeter for measurement.

What is the difference between dB and dBA?

dBA is A-weighted to approximate human hearing sensitivity and is commonly used for occupational noise guidance.

Noise Level Calculator

Combine decibel or dBA levels, add identical noise sources, estimate distance attenuation and review cautious NIOSH exposure guidance.

This calculator does not measure microphone noise. It calculates from entered sound levels and is not an official sound survey.

Input scale, dB or dBA

Hearing exposure guidance should use A-weighted dBA. If you enter dBA values, the combined result can be read as dBA.

Noise sources

Source 1, dBA

Level of identical sources, dBA

Number of identical sources

Original distance, m

New distance, m

Typical noise levels

These are rough reference values. Actual sound level depends on distance, room reflections, equipment and operating mode.

Add decibel levels correctly

English noise-level intent is calculator-first: combine dB or dBA sources logarithmically, add several identical sources and estimate how level changes with distance.

L_{t o t a l} = 10 lo g_{10} (i \sum 1 0^{L_{i} /10})

Ltotal is the combined sound level and Li are individual source levels.

L_{2} = L_{1} - 20 lo g_{10} (\frac{r _{2}}{r _{1}})

L1 is the level at distance r1 and L2 is the free-field estimate at r2.

The distance estimate assumes a point source in a free field. Walls, ground reflection, enclosures and directional sources can change real measurements.

dBA exposure caveats

Calculation, not measurement

This tool does not use your microphone and does not replace a calibrated sound level meter, dosimeter, workplace survey or legal compliance review.

NIOSH guidance uses A-weighted dBA and time-weighted exposure. Unweighted dB values are useful for physics calculations but should not be treated as a hearing-risk assessment.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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