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The frequency-weighted r.m.s. acceleration on this axis, measured at the seat.
From a seat-pad accelerometer on the machine doing its normal work, frequency-weighted to ISO 2631-1. The horizontal axes are multiplied by 1.4 before comparison, as the standard and the Directive require, so a modest fore-and-aft figure can still be the one that decides the day.
The frequency-weighted r.m.s. acceleration on this axis, measured at the seat.
From a seat-pad accelerometer on the machine doing its normal work, frequency-weighted to ISO 2631-1. The horizontal axes are multiplied by 1.4 before comparison, as the standard and the Directive require, so a modest fore-and-aft figure can still be the one that decides the day.
The frequency-weighted r.m.s. acceleration on this axis, measured at the seat.
From a seat-pad accelerometer on the machine doing its normal work, frequency-weighted to ISO 2631-1. The horizontal axes are multiplied by 1.4 before comparison, as the standard and the Directive require, so a modest fore-and-aft figure can still be the one that decides the day.
Hours spent on the machine while it is moving or working in the day.
The time the operator is seated on the machine while it is travelling or working — not the shift length, and not time parked with the engine idling on smooth ground.
Whether a vibration dose value is available to scale to the whole day.
The VDV weights shocks and jolts more heavily than the r.m.s. value does, and some measurement reports give it. It scales to a full day by the fourth root of time rather than the square root.
Daily whole-body vibration exposure, A(8)
0.476 m/s²
0.48 m/s² A(8), on the vertical (z) axis, is below the exposure action value of 0.5 m/s² A(8). 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.
- A(8) on the fore-and-aft (x) axis, ×1.4
- 0.36 m/s²
- A(8) on the side-to-side (y) axis, ×1.4
- 0.3 m/s²
- A(8) on the vertical (z) axis
- 0.48 m/s²
- Exposure time to reach the action value on the dominant axis
- 6.61 hours
- Exposure time to reach the limit value on the dominant axis
- 34.98 hours
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Whole-Body Vibration Exposure (A(8) and VDV) Calculator: 0.4763 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)
- ISO 2631-1:1997 and Directive 2002/44/EC, Annex B: the daily exposure A(8) is the highest of 1.4 awx, 1.4 awy and awz, each scaled by √(T ÷ 8 hours), where aw is the frequency-weighted r.m.s. acceleration on each axis measured at the seat
- Control of Vibration at Work Regulations 2005, regulation 4: for whole-body vibration, a daily exposure action value of 0.5 m/s² A(8) and an exposure limit value of 1.15 m/s² A(8)
- Directive 2002/44/EC, Article 3(2): a Member State may instead express the whole-body values as vibration dose values — 9.1 m/s^1.75 for the action value and 21 m/s^1.75 for the limit value — and ISO 2631-1 scales a dose measured over part of a day to the whole day by the fourth root of the ratio of the times
Inputs used
- Seat Vibration, Fore-and-Aft (x) Axis (m/s²)
- 0.3
- Seat Vibration, Side-to-Side (y) Axis (m/s²)
- 0.25
- Seat Vibration, Vertical (z) Axis (m/s²)
- 0.55
- Daily Exposure Time (hours)
- 6
- Also Scale a Measured Vibration Dose Value
- No
- Measured VDV, Dominant Axis (m/s^1.75)
- 6
- VDV Measurement Duration (minutes)
- 30
Intermediate steps
- A(8) on the fore-and-aft (x) axis, ×1.4
- 0.36 m/s²
- A(8) on the side-to-side (y) axis, ×1.4
- 0.3 m/s²
- A(8) on the vertical (z) axis
- 0.48 m/s²
- Exposure time to reach the action value on the dominant axis
- 6.61 hours
- Exposure time to reach the limit value on the dominant axis
- 34.98 hours
Confidence note: 0.48 m/s² A(8), on the vertical (z) axis, is below the exposure action value of 0.5 m/s² A(8). 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 accelerations must be frequency-weighted to ISO 2631-1 and measured at the seat on the machine doing its normal work; a figure from another machine, or the same machine on different ground, can differ by a factor of two.
- The r.m.s. A(8) under-represents shocks and jolts. Where the ride is jarring, the vibration dose value describes the exposure better, and the report should say which it used.
- Back pain in plant operators also comes from posture, long periods of sitting, climbing on and off and manual handling, none of which a vibration figure measures.
- The UK regulations use A(8) only; the VDV values are the Directive's alternative, which a Member State may choose instead.
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 citations3
- ISO 2631-1:1997 and Directive 2002/44/EC, Annex B: the daily exposure A(8) is the highest of 1.4 awx, 1.4 awy and awz, each scaled by √(T ÷ 8 hours), where aw is the frequency-weighted r.m.s. acceleration on each axis measured at the seat
- Control of Vibration at Work Regulations 2005, regulation 4: for whole-body vibration, a daily exposure action value of 0.5 m/s² A(8) and an exposure limit value of 1.15 m/s² A(8)
- Directive 2002/44/EC, Article 3(2): a Member State may instead express the whole-body values as vibration dose values — 9.1 m/s^1.75 for the action value and 21 m/s^1.75 for the limit value — and ISO 2631-1 scales a dose measured over part of a day to the whole day by the fourth root of the ratio of the times
Which documents these citations point at
Standards referenced: ISO 2631-1 (International Organization for Standardization, International).
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