SettingsSettings for this calculationUS
The tool's vibration total value, ahv, in use — 0 leaves the row out.
The three-axis vibration total value in metres per second squared, as the tool is actually used. A measurement of the tool on the job is best; the figure declared in the handbook under the test standard for that tool type often understates real use, and CEN/TR 15350 describes how to turn a declared value into an in-use estimate.
The time the tool is actually vibrating in the hands in the day — minutes divided by 60.
Trigger time, not time holding the tool or time on the task. It is usually much shorter than it feels: a person 'breaking out all morning' may have the breaker running for well under an hour. Timing a representative spell of work gives the best figure.
The tool's vibration total value, ahv, in use — 0 leaves the row out.
The three-axis vibration total value in metres per second squared, as the tool is actually used. A measurement of the tool on the job is best; the figure declared in the handbook under the test standard for that tool type often understates real use, and CEN/TR 15350 describes how to turn a declared value into an in-use estimate.
The time the tool is actually vibrating in the hands in the day — minutes divided by 60.
Trigger time, not time holding the tool or time on the task. It is usually much shorter than it feels: a person 'breaking out all morning' may have the breaker running for well under an hour. Timing a representative spell of work gives the best figure.
The tool's vibration total value, ahv, in use — 0 leaves the row out.
The three-axis vibration total value in metres per second squared, as the tool is actually used. A measurement of the tool on the job is best; the figure declared in the handbook under the test standard for that tool type often understates real use, and CEN/TR 15350 describes how to turn a declared value into an in-use estimate.
The time the tool is actually vibrating in the hands in the day — minutes divided by 60.
Trigger time, not time holding the tool or time on the task. It is usually much shorter than it feels: a person 'breaking out all morning' may have the breaker running for well under an hour. Timing a representative spell of work gives the best figure.
The tool's vibration total value, ahv, in use — 0 leaves the row out.
The three-axis vibration total value in metres per second squared, as the tool is actually used. A measurement of the tool on the job is best; the figure declared in the handbook under the test standard for that tool type often understates real use, and CEN/TR 15350 describes how to turn a declared value into an in-use estimate.
The time the tool is actually vibrating in the hands in the day — minutes divided by 60.
Trigger time, not time holding the tool or time on the task. It is usually much shorter than it feels: a person 'breaking out all morning' may have the breaker running for well under an hour. Timing a representative spell of work gives the best figure.
Daily hand-arm vibration exposure, A(8)
2.25 m/s²
2.25 m/s² A(8) is below the exposure action value of 2.5 m/s² A(8) (100 points). These are the UK and EU regulations' values, and ANSI S2.70 uses the same two in the US. The exposure is 81 points in all. The regulations require the risk from vibration to be eliminated or reduced as far as reasonably practicable at every level, so no figure here is a finding that the exposure is acceptable.
- Exposure points (100 is the action value, 400 the limit value)
- 81 points
- Tool 1: partial exposure
- 1.75 m/s²
- Tool 2: partial exposure
- 1.41 m/s²
- Tool 1: trigger time to reach the action value on its own
- 1.02 hours
- Tool 2: trigger time to reach the action value on its own
- 3.13 hours
- Tool 1: trigger time to reach the limit value on its own
- 4.08 hours
- Tool 2: trigger time to reach the limit value on its own
- 12.5 hours
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Hand-Arm Vibration Exposure (A(8)) and Points Calculator: 2.25 m/s² — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- BS EN ISO 5349-1:2001: the daily exposure A(8) = ahv × √(T ÷ T0), with T0 = 8 hours, and for several tools A(8) = √(A1(8)² + A2(8)² + … + An(8)²)
- Control of Vibration at Work Regulations 2005, regulation 4, and Directive 2002/44/EC, Article 3: for hand-arm vibration, a daily exposure action value of 2.5 m/s² A(8) and an exposure limit value of 5 m/s² A(8)
- HSE L140 (Hand-arm vibration at work): exposure points = 2 × ahv² × T, with T in hours, so 100 points is the exposure action value and 400 points the exposure limit value
- ANSI S2.70-2006 (US): the same daily exposure action value of 2.5 m/s² and limit value of 5.0 m/s², on the ISO 5349-1 A(8) basis
Inputs used
- Tool 1 Vibration Magnitude (m/s²)
- 7
- Tool 1 Trigger Time (hours)
- 0.5
- Tool 2 Vibration Magnitude (m/s²)
- 4
- Tool 2 Trigger Time (hours)
- 1
- Tool 3 Vibration Magnitude (m/s²)
- 0
- Tool 3 Trigger Time (hours)
- 0
- Tool 4 Vibration Magnitude (m/s²)
- 0
- Tool 4 Trigger Time (hours)
- 0
Intermediate steps
- Exposure points (100 is the action value, 400 the limit value)
- 81 points
- Tool 1: partial exposure
- 1.75 m/s²
- Tool 2: partial exposure
- 1.41 m/s²
- Tool 1: trigger time to reach the action value on its own
- 1.02 hours
- Tool 2: trigger time to reach the action value on its own
- 3.13 hours
- Tool 1: trigger time to reach the limit value on its own
- 4.08 hours
- Tool 2: trigger time to reach the limit value on its own
- 12.5 hours
Confidence note: 2.25 m/s² A(8) is below the exposure action value of 2.5 m/s² A(8) (100 points). These are the UK and EU regulations' values, and ANSI S2.70 uses the same two in the US. The exposure is 81 points in all. The regulations require the risk from vibration to be eliminated or reduced as far as reasonably practicable at every level, so no figure here is a finding that the exposure is acceptable.
What this calculation does not cover
- The magnitude must be the tool's three-axis vibration total value in use. A handbook's declared value is measured under a standard test, not on your job, and often understates real use.
- Trigger time is the time the tool is vibrating in the hands, not the time spent on the task, and overestimating it is as common as underestimating the magnitude.
- The A(8) describes the dose; the harm — vibration white finger and carpal tunnel syndrome — also depends on grip force, cold and wet hands and the individual, which is why the regulations require health surveillance for those at risk, not only a number.
- It covers hand-arm vibration only. Driving or riding vibrating plant is whole-body vibration, a separate exposure with different values.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-21 · v1.0.0
Regulatory standards & verification citations4
- BS EN ISO 5349-1:2001: the daily exposure A(8) = ahv × √(T ÷ T0), with T0 = 8 hours, and for several tools A(8) = √(A1(8)² + A2(8)² + … + An(8)²)
- Control of Vibration at Work Regulations 2005, regulation 4, and Directive 2002/44/EC, Article 3: for hand-arm vibration, a daily exposure action value of 2.5 m/s² A(8) and an exposure limit value of 5 m/s² A(8)
- HSE L140 (Hand-arm vibration at work): exposure points = 2 × ahv² × T, with T in hours, so 100 points is the exposure action value and 400 points the exposure limit value
- ANSI S2.70-2006 (US): the same daily exposure action value of 2.5 m/s² and limit value of 5.0 m/s², on the ISO 5349-1 A(8) basis
Which documents these citations point at
Standards referenced: ISO 5349-1 (International Organization for Standardization, International).
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