Free exposure calculator
HAVS calculator for daily hand-arm vibration exposure
This free HAVS calculator works out a worker's daily hand-arm vibration exposure from each tool's vibration magnitude and trigger time, in HSE exposure points and m/s² A(8). It shows where the day sits against the two thresholds in regulation 4 of the Control of Vibration at Work Regulations 2005: the exposure action value of 2.5 m/s² A(8), which is 100 points, and the exposure limit value of 5 m/s² A(8), which is 400 points.
This tool estimates daily hand-arm vibration exposure using the HSE exposure points system, against the values in the Control of Vibration at Work Regulations 2005. It is a screening aid, not a substitute for a vibration risk assessment. Results depend on the vibration magnitude you enter: manufacturer declared values can differ from real in-use vibration, and the HSE recommends using measured or published in-use data where available. Any work that exposes employees to vibration needs a risk assessment, and if your results approach or exceed the exposure action value you also need a programme of control measures and health surveillance. Ask Opus Safety for who to speak to.
How to use the HAVS calculator
- List every vibrating tool the worker uses in a typical day.
- Enter each tool's vibration magnitude in m/s², or pick a starting value from the HSE indicative values in the tool list.
- Enter the trigger time for each tool: the time it is running in the worker's hands, in hours and minutes.
- Read the total. The calculator adds the points from every tool and converts them to a single A(8) figure for the day.
- Download the PDF report if you want a record. The result shows on screen without it; the report asks for your name, email and company.
Trigger time can be much shorter than the time a job takes, because a tool is put down between cuts, holes and passes. Timing real use on site gives a better figure than an estimate from the job sheet.
How exposure points work
Exposure points let you add up vibration from different tools with simple arithmetic. A tool earns points at a rate of 2 × its magnitude squared for every hour of trigger time, so 100 points always equals the exposure action value and 400 points the exposure limit value.
Because the magnitude is squared, it matters more than time:
- A tool at 2.5 m/s² earns 12.5 points an hour and reaches the action value after a full 8 hours.
- A tool at 5 m/s² earns 50 points an hour. It reaches the action value after 2 hours and the limit value after 8.
- A tool at 10 m/s² earns 200 points an hour. It reaches the action value after 30 minutes and the limit value after 2 hours.
The A(8) figure is the same exposure expressed as an 8-hour average, which is how Schedule 1 of the Regulations calculates daily exposure.
What the action and limit values mean for you
Where the exposure action value is likely to be reached or exceeded, regulation 6(2) of the Control of Vibration at Work Regulations 2005 requires you to reduce exposure to as low a level as is reasonably practicable through a programme of organisational and technical measures, such as lower-vibration tools, shorter trigger times or job rotation. Regulation 7 of the same Regulations requires health surveillance for employees likely to be exposed at or above the action value, and where your risk assessment identifies a risk to health that surveillance can detect.
The exposure limit value is the most a worker may be exposed to in a day. If it is exceeded, regulation 6(4) of the Control of Vibration at Work Regulations 2005 requires you to bring exposure back below it at once, find out why it happened and change your controls to stop it happening again.
Where to find your tools' vibration magnitudes
Start with the vibration emission value the manufacturer declares in the tool's handbook. It is measured under standard test conditions, and regulation 5(2) of the Control of Vibration at Work Regulations 2005 requires you to assess exposure by observing the work, using information on the probable magnitude in your particular working conditions, and measuring where necessary. Worn accessories, the material being worked and the way the tool is held all change what reaches the hands.
If a worker is at or above the action value
The calculator tells you where a day sits. From there the law expects a programme of controls, health surveillance with a health record kept for each employee, and information, instruction and training for the people exposed, all built on the risk assessment that regulation 5 of the Control of Vibration at Work Regulations 2005 requires for any work liable to expose employees to vibration risk.
Opus runs HAVS health surveillance on your site. Our Occupational Health technicians start every employee at Tier 1 (a health questionnaire) and Tier 2 (annual screening questionnaire), and anyone reporting symptoms is referred on to Tier 3 (clinical assessment) or Tier 4 (formal diagnosis by a doctor). You receive an outcome for each employee and a site report flagging anyone who needs follow-up.
Frequently asked questions
What is hand-arm vibration syndrome (HAVS)?
HAVS is damage to the nerves, blood vessels and joints of the hand and arm caused by regular use of vibrating tools such as breakers, grinders, sanders and impact wrenches. Early signs include tingling, numbness and fingers turning white in the cold. It can be prevented, but once the damage is done it cannot be reversed, which is why the law focuses on controlling exposure before symptoms appear.
What is the exposure action value for hand-arm vibration?
It is a daily exposure of 2.5 m/s² A(8), equal to 100 exposure points, set by regulation 4 of the Control of Vibration at Work Regulations 2005. Where exposure is likely to reach or exceed it, you must run a programme of measures to reduce exposure and provide suitable health surveillance for the employees concerned.
What is the exposure limit value for hand-arm vibration?
It is a daily exposure of 5 m/s² A(8), equal to 400 exposure points. It is the most a worker may be exposed to in a day. If it is exceeded, you must bring exposure below it immediately, identify why, and change your controls.
How are HAVS exposure points calculated?
Each tool earns points at a rate of 2 × its vibration magnitude squared (in m/s²) for every hour of trigger time. Points from all the tools used that day are added together. 100 points equals the exposure action value and 400 points the exposure limit value.
Can vibration exposure be averaged over a week?
Only in a narrow case. Regulation 6(5) of the Control of Vibration at Work Regulations 2005 allows weekly averaging where a worker's exposure is usually below the action value but varies markedly and may occasionally exceed the limit value, and only if the weekly average stays below the limit value, the risk is shown to be lower than constant exposure at the limit, risk is reduced to as low a level as is reasonably practicable and the employees are under increased health surveillance where it is appropriate.
Where do I find the vibration magnitude for a tool?
The manufacturer's declared value in the tool handbook is the place to start. Because it is measured under test conditions, check it against how the tool is used on your site, and have exposure measured if you are unsure.
Does the calculator replace a vibration risk assessment?
No. It works out exposure from the figures you enter. A risk assessment under regulation 5 of the Control of Vibration at Work Regulations 2005 also looks at how the work is done, who is at particular risk and what controls are needed.
Is the HAVS calculator free?
Yes. You can use it as often as you like, and the result shows on screen. The PDF report asks for your name, email and company.