Vibration Exposure (A8) Calculator

Work out vibration exposure (a8) instantly with clear inputs, formula shown and shareable results.

About Vibration Exposure (A8) Calculator

Daily vibration exposure A(8) normalises magnitude to an eight hour reference using the square root of the time ratio, because vibration dose accumulates with the square of magnitude. That relationship is why halving exposure time only reduces A(8) by about thirty percent, while switching to a tool with half the magnitude halves it outright.

Formulas

Daily exposure

A(8) = a x sqrt(T / 8)

Time to a limit

Hours = 8 x (limit / magnitude)²

Worked example

With the default values below, Vibration Exposure (A8) Calculator returns Daily exposure A(8) of 3.062. Change any input above and every figure here is recalculated in your browser.

Inputs used

Vibration magnitudeminimum 0.01 m/s²: 5 m/s²
Daily exposure timeaccepts 0.01–24 h: 3 h
Exposure limit valueminimum 0.01 m/s²: 5 m/s²
Exposure action valueminimum 0.01 m/s²: 2.5 m/s²

Results

Daily exposure A(8): 3.062 m/s²
Share of the exposure limit value: 61.2% %
Time to reach the limit value: 8.00 h
Assessment: Above the action value — controls and health surveillance required

Step by step

1Values used
2Daily exposure
3Time to a limit
4Daily exposure A(8)= 3.062 m/s²
5Share of the exposure limit value= 61.2 %
6Time to reach the limit value= 8.00 h
7Assessment= Above the action value — controls and health surveillance required

Assumptions and limits

The result is derived only from the 4 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 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Vibration risk assessment and health surveillance must follow the vibration regulations in force and be carried out by a competent person.

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

Preliminary estimate only. Vibration risk assessment and health surveillance must follow the vibration regulations in force and be carried out by a competent person.

Frequently Asked Questions

How is the Vibration Exposure (A8) figure worked out?

A(8) = a x sqrt(T / 8). Daily vibration exposure A(8) normalises magnitude to an eight hour reference using the square root of the time ratio, because vibration dose accumulates with the square of magnitude.

Which is more effective, less time or a better tool?

A better tool. Because A(8) scales linearly with magnitude but only with the square root of time, reducing magnitude gives roughly twice the benefit per unit of change.

What values do I need to enter?

This calculator takes 4 inputs: Vibration magnitude, Daily exposure time, Exposure limit value, Exposure action value. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.