REBA Ergonomic Risk Assessment

How the REBA score is built

REBA (Rapid Entire Body Assessment) scores posture in two branches that are combined at the end. Branch A covers the trunk, neck, and legs; branch B covers the upper arm, lower arm, and wrist. Each joint gets a 1-4 score from its flexion/extension angle, with extra points added for twisting, side-bending, abduction, or a raised shoulder — a supported arm is the one adjustment that subtracts a point.

Each branch's joint scores are combined through a lookup table (Table A for trunk/neck/legs, Table B for upper arm/lower arm/wrist) rather than simply added together, so the same joint score contributes a different amount depending on what the other joints in its branch are doing. Table A's result is then adjusted for handled load (a further +1 at 5-10kg, +2 at 10kg or more, plus +1 more if the load is applied with a sudden shock) and Table B's result is adjusted for hand-to-object coupling quality.

The two adjusted branch scores go through a third lookup table (Table C) to produce a single combined posture score. Static holding, small repeated motions, and rapid large postural changes each add one more point on top of that — these are activity-pattern penalties, not posture penalties, so they apply after the table lookup rather than changing any joint score.

The final REBA score maps to five risk bands, each with a corresponding action level: negligible (score 1, action 0 — no action needed) through very high (score 11 and above, action 4 — implement change now). The bands in between are low (2-3, action 1: may be needed), medium (4-7, action 2: needed soon), and high (8-10, action 3: needed soon, investigate).

When to Use This

• Screening a manual-handling or assembly task where a worker holds an awkward trunk, neck, or arm posture for a sustained period.
• Comparing two workstation layouts or task methods by their REBA score to see which reduces postural load.
• Documenting an ergonomic hazard assessment as part of a broader occupational health and safety review.

Common Mistakes

• Scoring a single instantaneous posture when the task actually cycles through several distinct postures — REBA is meant to be applied to the worst-case posture observed during the task, not an average.
• Forgetting the activity-pattern checkboxes (static holding, repeated small-range motion, rapid large change) — these add directly to the final score and are easy to overlook since they sit outside the joint-angle inputs.
• Treating hand-to-object coupling as irrelevant — a poor or unacceptable grip adds points to branch B independently of wrist angle, so an otherwise neutral wrist posture can still push the score up.
• Reading the action level as a strict deadline rather than a priority signal — REBA ranks urgency for further investigation and intervention, it does not by itself certify a task as compliant or non-compliant with a specific regulation.

FAQ

What do the REBA score and action level actually mean?

The REBA score is a single combined measure of postural, load, and activity risk, starting at a minimum of 1. It maps to an action level from 0 to 4: 0 means no action needed, 1 means action may be needed, 2 and 3 mean action is needed soon (3 also calls for further investigation), and 4 means implement change now. Higher scores mean higher priority for redesigning the task, not an automatic pass/fail verdict.

Why does adding a checkbox like "trunk twisted" sometimes change the score by more than one point?

Individual joint adjustments (twist, side-bend, shoulder raise, abduction) do add a flat +1 (or -1 for a supported arm) to that joint's own score, but that adjusted joint score then feeds into a lookup table together with the other joints in its branch — the table, not a simple sum, produces the branch score. So a one-point change in a joint score can shift the branch score, and the branch score in turn shifts the final table lookup, by more or less than one point depending on where the surrounding values fall in the table.

Does a heavier load always increase the score more than a shock force does?

No — load and shock are scored independently and then added together. Handled load adds up to +2 (0kg-under-5kg = +0, 5kg-under-10kg = +1, 10kg or more = +2), and a sudden or jerky application of that load (shock force) adds a further flat +1 regardless of the load's magnitude. A light load applied with a shock can add as much to the score as a moderate load applied smoothly.

What happens if I leave hand-to-object coupling unset?

This calculator does not expose a coupling input and always evaluates with coupling treated as 'good' (+0 to branch B) — the underlying calculation's default when coupling is not separately specified. If your task involves a poor or unacceptable grip, that adds real risk this score will not capture — assess coupling separately when the task involves handles, gloves, or an awkward grasp.