Disability Rating Calculator
Calculate combined whole person impairment (WPI) using the AMA Guides Combined Values formula for upper extremity, lower extremity, and spine impairments.
About this calculator
Combining multiple body-part impairment ratings into a single whole person impairment (WPI) figure is not as simple as adding the percentages together -- doing that could push a combined rating past 100% impairment for someone who is clearly not totally impaired. Instead, workers' compensation and disability rating practice built on the American Medical Association's Guides to the Evaluation of Permanent Impairment, Sixth Edition (published 2008), applies the Combined Values Chart formula: Combined = A + B x (1 - A/100), where A and B are two impairment percentages. This calculator applies that formula pairwise across all three inputs -- Upper Extremity Impairment, Lower Extremity Impairment, and Spine Impairment -- combining the first two, then combining that intermediate result with the third.
The formula is mathematically equivalent to 100 x (1 - (1-A/100)(1-B/100)(1-C/100)), which makes an important property clear: combining is both order-independent and never exceeds 100%, since each additional impairment is applied only to the "remaining" un-impaired portion of the person rather than added on top of what's already counted -- the same body-part impairment, evaluated first or last, produces the same Combined WPI. ADL Impact is this calculator's own five-tier bucketing of the resulting Combined WPI into rough real-world categories (minimal through total), meant as a plain- language summary rather than a term drawn directly from the AMA Guides itself. This tool is for educational and planning purposes only -- an actual disability rating requires a qualified medical evaluator applying the full AMA Guides methodology (or the specific edition/state schedule that applies to a given claim), not a general calculator.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
Combined WPI
29.6%
ADL Impact
2 (1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total)
Figures current as of 2008. Source: American Medical Association. Guides to the Evaluation of Permanent Impairment, Sixth Edition. Chicago, IL: AMA Press; 2008.
How to Use This Calculator
- Enter Upper Extremity Impairment, Lower Extremity Impairment, and Spine Impairment.
- Review Combined WPI (%) and ADL Impact ((1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total)).
- Use Functional Loss (%) to inform your decision.
How the result changes with Upper Extremity Impairment
| Upper Extremity Impairment | Combined WPI | ADL Impact |
|---|---|---|
| 7.5 | 23.4% | 2 (1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total) |
| 11 | 26.3% | 2 (1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total) |
| 23 | 36.2% | 3 (1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total) |
| 38 | 48.7% | 3 (1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Total) |
What each input means
- Upper Extremity Impairment
- Whole person impairment percentage for upper extremity (shoulder, arm, hand) per AMA Guides.
- Lower Extremity Impairment
- Whole person impairment percentage for lower extremity (hip, knee, ankle, foot) per AMA Guides.
- Spine Impairment
- Whole person impairment percentage for spine (cervical, thoracic, lumbar) per AMA Guides.
How this is calculated
Worked example, using the default values
- Identify Input ParametersUpper Extremity Impairment = 15, Lower Extremity Impairment = 10, Spine Impairment = 8 = 3 input(s) provided
- Calculate Combined WPICombined WPI29.6 = 29.6%
- Calculate ADL ImpactADL Impact2 = 2
- Calculate Functional LossFunctional Loss29.6 = 29.6%
Figures and sources
- AMA Guides Combined Values Chart formula (2008) — American Medical Association. Guides to the Evaluation of Permanent Impairment, Sixth Edition. Chicago, IL: AMA Press; 2008.
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't Combined WPI just add the three impairment percentages together?
Simple addition could easily push a combined rating past 100%, which doesn't make physical sense -- a person can't be more than fully impaired. The AMA Guides Combined Values formula instead applies each additional impairment only to the portion of the person not already accounted for by the prior impairments, which is why Combined WPI always comes out lower than the sum of the three inputs (except when one of them is zero).
Does it matter which impairment is entered first when combining all three?
No -- the Combined Values formula is mathematically order-independent. Combining Upper Extremity Impairment with Lower Extremity Impairment first and then Spine Impairment produces exactly the same Combined WPI as combining them in any other order, because the underlying formula is equivalent to multiplying together each impairment's "unaffected" complement (1 minus the impairment, as a fraction) regardless of sequence.
How much higher is Combined WPI when Spine Impairment increases from 8% to 20%?
It depends on the other two values, since the formula applies each additional impairment to the portion of the person not already impaired by the others -- but raising Spine Impairment always raises Combined WPI, holding Upper Extremity Impairment and Lower Extremity Impairment fixed. The increase is somewhat less than the raw 12-point difference in Spine Impairment alone, because that 12 points is applied only to the remaining unimpaired share of the person after the other two impairments are already factored in.
Is ADL Impact an official AMA Guides category?
No -- ADL Impact is this calculator's own simplified five-tier summary (Minimal, Mild, Moderate, Severe, Total) built from the Combined WPI percentage, meant to give a plain-language sense of real-world activities-of-daily-living impact. It is not an official term or classification from the AMA Guides to the Evaluation of Permanent Impairment itself, and should not be cited as one.
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