Free tool for UK builders
HAVS exposure points calculator
Work out one person’s daily hand-arm vibration exposure from the tools they use. You get exposure points and A(8) for each tool and for the day, checked against the exposure action value and the exposure limit value. It uses the method in HSE’s guidance L140.
Work out a day’s vibration exposure
Add each vibrating tool one person uses in a day, with its vibration magnitude and the time their hands are on it while it runs (the trigger time). Everything is worked out in your browser. Nothing you enter is sent to us.
Enter a vibration magnitude and a trigger time for at least one tool.
Exposure action value: 100 points (2.5 m/s² A(8)). Exposure limit value: 400 points (5 m/s² A(8)). Points are rounded to the nearest whole point, so HSE’s ready-reckoner, which rounds its table, can differ by a few points.
This is a guide. Your risk assessment decides the controls.
The calculator only does the arithmetic. The result is only as good as the figures you enter, so use it alongside your risk assessment, not instead of it.
How the calculation works
The calculator uses the formulas in Appendix 1 of HSE’s guidance L140. In each one, a is the tool’s vibration magnitude in m/s² and T is the trigger time in hours.
Exposure points for a tool
points = 2 × a² × T
Partial exposure for a tool
A(8) = a × √(T ÷ 8)
Daily exposure from several tools
A(8) = √(A1(8)² + A2(8)² + A3(8)² + …)
Daily exposure from total points
A(8) = 2.5 × √(points ÷ 100)
Time for one tool to reach the action value and the limit value
action value: (2.5 ÷ a)² × 8 hours · limit value: (5 ÷ a)² × 8 hours
Points add up across tools, so you can total a day by adding each tool’s points. 100 points equals the exposure action value of 2.5 m/s² A(8). 400 points equals the exposure limit value of 5 m/s² A(8).
HSE’s worked example: a welder uses an angle grinder at 8 m/s² for 3 hours and a needle scaler at 12 m/s² for 30 minutes. HSE’s ready-reckoner gives 385 and 145 points, 530 in total, which is above the exposure limit value. This calculator gives 384 and 144 points, 528 in total, because HSE’s table rounds its values. Press Use HSE’s worked example to load it.
What the action and limit values mean
The Control of Vibration at Work Regulations 2005 set a daily exposure action value of 2.5 m/s² A(8) and a daily exposure limit value of 5 m/s² A(8) for hand-arm vibration (regulation 4).
If the risk cannot be eliminated at source and the action value is likely to be reached or exceeded, the employer must reduce exposure to as low a level as is reasonably practicable. They do this with a programme of organisational and technical measures suited to the activity (regulation 6(2)).
Subject to limited exceptions in the Regulations, the employer must make sure employees are not exposed above the exposure limit value (regulation 6(4)).
Research for HSE found that an A(8) estimate can be uncertain by at least ±20%. If your estimate is close to the action or limit value, HSE’s guidance says to assume it is likely to be exceeded and act on that (L140, Appendix 1, paragraph 13). That is why the calculator warns you between 64 and 100 points, and between 255 and 400 points. HSE’s ready-reckoner treats those bands as likely to be at or above the action value, and likely to be above the limit value (L140, Appendix 1, paragraph 27).
Where to get the figures
Use a vibration magnitude that represents the tool you will use and the way you will use it (L140, paragraph 29). HSE lists sources such as the emission value declared in the equipment handbook, the supplier, internet databases, trade associations, HSE’s website and measurements in your own workplace. Check that the figure is reasonably representative of the tool as used in your work (L140, paragraphs 29 and 30).
Trigger time is the time the person is actually exposed to the vibration, which HSE also calls contact time (L140, paragraph 102). HSE suggests you could measure the trigger time over, for example, half an hour and use it to estimate the trigger time for the full shift.
What this calculator does not do
- It does not measure vibration. It works out exposure from the figures you enter.
- It covers hand-arm vibration only. Whole-body vibration has its own action and limit values in the Regulations.
- It does not decide the controls your workers need. Your risk assessment does.
Put the controls in your paperwork
Write the vibration controls into your RAMS
Describe the job in plain English and The Site Book prepares a site-specific RAMS draft for your competent review. Your first project is free.
Start free →Brief the crew with a free toolbox talk
The free Hand-Arm Vibration (HAVS) toolbox talk has key points, do’s and don’ts, and questions to check understanding. In The Site Book, delivering toolbox talks and collecting signatures is on Pro and above.
Read the toolbox talk →Related
More free tools: all free tools and templates.
Sources
- The Control of Vibration at Work Regulations 2005, regulation 4 (exposure limit values and action values) — legislation.gov.uk · Accessed 27 October 2026
- The Control of Vibration at Work Regulations 2005, regulation 6 (elimination or control of exposure) — legislation.gov.uk · Accessed 27 October 2026
- The Control of Vibration at Work Regulations 2005, Schedule 1 (hand-arm vibration daily exposure) — legislation.gov.uk · Accessed 27 October 2026
- Hand-arm vibration: Guidance on Regulations (L140, second edition, 2019), Appendix 1 — Health and Safety Executive · Accessed 27 October 2026
- The hand-arm vibration exposure calculator — Health and Safety Executive · Accessed 27 October 2026
- Vibration risk assessment (the exposure points system) — Health and Safety Executive · Accessed 27 October 2026