Noise Exposure Level (LEX) Calculator

Work out noise exposure level (lex) instantly with clear inputs, formula shown and shareable results.

About Noise Exposure Level (LEX) Calculator

Daily noise exposure normalised to eight hours uses the equal-energy three decibel rule: LEX,8h = L + 10 log10(T/8). Halving the exposure time therefore reduces the daily level by three decibels. Exposure points express the same thing on a linear scale where 100 points equals 85 dB, which makes combining several tasks a matter of addition.

Formulas

Daily exposure level

LEX,8h = L + 10 log10(T / 8)

Exposure points

Points = 100 x 10^((LEX - 85) / 10)

Worked example

With the default values below, Noise Exposure Level (LEX) Calculator returns Daily noise exposure level of 86.75. Change any input above and every figure here is recalculated in your browser.

Inputs used

A-weighted sound levelaccepts 40–140 dBA: 88 dBA
Exposure durationaccepts 0.05–24 h: 6 h

Results

Daily noise exposure level: 86.75 dB(A) LEX,8h
Daily dose against 85 dB: 149.6% %
Exposure points: 149.6
Assessment: At or above the upper action value — hearing protection mandatory

Step by step

1Values used
2Daily exposure level
3Exposure points
4Daily noise exposure level= 86.75 dB(A) LEX,8h
5Daily dose against 85 dB= 149.6 %
6Exposure points= 149.6
7Assessment= At or above the upper action value — hearing protection mandatory

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Noise risk assessment must be carried out by a competent person to the noise regulations in force.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Noise risk assessment must be carried out by a competent person to the noise regulations in force.

Frequently Asked Questions

How is the Noise Exposure Level (LEX) figure worked out?

LEX,8h = L + 10 log10(T / 8). Daily noise exposure normalised to eight hours uses the equal-energy three decibel rule: LEX,8h = L + 10 log10(T/8).

Why use points rather than decibels?

Decibels cannot be added arithmetically. Points can, so the contributions of several noisy tasks in a shift are simply summed and compared with the 100 point action value.

What values do I need to enter?

This calculator takes 2 inputs: A-weighted sound level, Exposure duration. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.