Calculator Input Form
Enter impairment ratings from your own review. Use conversion factors when a regional value must be converted to whole person impairment.
Example Data Table
This sample shows how entered ratings, conversion factors, adjustments, and apportionment can be organized.
| Component | Rating % | Factor | Adjustment % | Pre-existing % | Case-related % |
|---|---|---|---|---|---|
| Spine | 12 | 1.00 | 0 | 10 | 100 |
| Upper Extremity | 18 | 0.60 | 5 | 0 | 100 |
| Lower Extremity | 15 | 0.40 | 0 | 20 | 90 |
| Neurologic | 8 | 1.00 | 0 | 0 | 100 |
Formula Used
Component WPI = Entered Rating × Conversion Factor
Adjusted WPI = Component WPI × (1 + Clinical Adjustment ÷ 100)
Case-related WPI = Adjusted WPI × (1 − Pre-existing % ÷ 100) × (Case-related % ÷ 100)
Combined = A + B × (100 − A) ÷ 100
The combined values method prevents simple addition from exceeding logical whole person limits. This page applies the formula sequentially to each entered component.
How to Use This Calculator
- Enter the claimant, evaluator, case number, and evaluation date.
- Add impairment ratings for each applicable body system or component.
- Use a conversion factor of 1.00 when the value is already WPI.
- Enter any clinical adjustment percentage supported by your documentation.
- Add pre-existing and case-related percentages for apportionment review.
- Select the rounding style and combination order.
- Press the calculate button to view results above the form.
- Download the CSV or PDF file for documentation.
Impairment Rating Overview
Purpose of the Tool
An impairment calculation can involve many small ratings. Each value may come from a different body region, diagnosis, examination finding, or evaluator judgment. This calculator helps organize those values in one clean worksheet. It gives a structured estimate of whole person impairment. It also shows the effect of apportionment and adjustment. The goal is clarity, not replacement of professional review.
Why Combined Values Matter
Impairment percentages should not always be added directly. A person cannot usually be treated as more than one hundred percent impaired. Combined values reduce each later rating against the remaining unimpaired portion. For example, a second rating is applied only to what remains after the first rating. This approach keeps totals more realistic and easier to compare.
Using Conversion Factors
Some ratings are already stated as whole person impairment. Others may describe a regional impairment. A conversion factor lets you translate a regional value into a whole person estimate. This page does not provide official conversion tables. You must enter factors from the correct source, edition, jurisdiction, or evaluator worksheet. Use one point zero when no conversion is needed.
Adjustment and Apportionment
Clinical adjustment can raise or reduce a component before final combination. Apportionment can separate pre-existing conditions from the case-related portion. These entries make the worksheet more flexible. They also help explain why a final number differs from the raw rating. Always keep notes about evidence, diagnosis, examination findings, and reasoning.
Documentation Benefits
The result table gives each component, adjustment, deduction, and final case-related value. The graph makes differences easier to see. The CSV export helps with spreadsheets. The PDF export supports file review and discussion. A careful worksheet can reduce confusion during claims review, medical reporting, legal review, and settlement planning.
Frequently Asked Questions
1. Is this an official AMA Guides calculator?
No. This is an educational worksheet. It does not reproduce official tables. A qualified evaluator should verify every rating, method, edition, and jurisdiction rule.
2. What does WPI mean?
WPI means whole person impairment. It expresses impairment as a percentage of the whole person rather than only one body part or region.
3. Why is the combined value lower than simple addition?
The combined method applies each later rating to the remaining unimpaired portion. This prevents unrealistic totals from simple addition.
4. What conversion factor should I use?
Use the factor required by your evaluator worksheet, edition, jurisdiction, or source document. Use 1.00 when the entered rating is already WPI.
5. Can I enter negative adjustments?
Yes. Negative adjustment percentages reduce the component value. Use them only when supported by the chosen evaluation method and documentation.
6. What does pre-existing percentage mean?
It represents the portion of adjusted impairment attributed to prior conditions. The calculator deducts that portion before final combination.
7. What does case-related percentage mean?
It represents the remaining portion linked to the current case. The calculator multiplies adjusted impairment by this percentage after pre-existing deduction.
8. Can I use the PDF in a claim file?
You can use it as a worksheet attachment. It should not replace the evaluator report, official rating source, or legal review.