How VA Disability Ratings Are Calculated (With Examples)

Understanding how the VA calculates disability ratings helps veterans know what to expect from their claim and whether their combined rating accurately reflects their service-connected conditions. The VA does not simply add percentages together. It uses a specific method often called "VA math" to combine ratings while accounting for the "whole person" efficiency concept.

This article explains the process in plain English, including the bilateral factor and Total Disability based on Individual Unemployability (TDIU), with clear worked examples.

The basic rating process

The VA assigns each service-connected condition a rating from 0 to 100 percent in increments of 10 percent, based on severity and the diagnostic code criteria in the VA Schedule for Rating Disabilities (38 CFR Part 4).

When a veteran has multiple conditions, the VA combines them using a combined ratings table rather than simple addition. The idea is that each additional disability affects the remaining "efficiency" of the whole person, not a fixed total that percentages simply subtract from.

How VA math works step by step

List all individual ratings in descending order, from highest to lowest. Start with the highest rating, then take each subsequent rating as a percentage of the remaining efficiency, meaning 100 minus the current combined percentage. Add that value to the running total and repeat for each additional rating. Round the final combined value to the nearest 10 percent only at the very end.

Example 1: Simple combination

A veteran has two conditions rated at 50 percent and 30 percent. Start with 50 percent, leaving 50 percent of remaining efficiency. Thirty percent of that remaining 50 percent equals 15 percent. The combined total is 50 plus 15, or 65 percent, which rounds to 70 percent.

Example 2: More conditions

A veteran has ratings of 40 percent, 30 percent, and 20 percent. Start with 40 percent, leaving 60 percent remaining. Thirty percent of 60 percent is 18 percent, bringing the combined total to 58 percent. Twenty percent of the remaining 42 percent is approximately 8.4 percent, bringing the total before rounding to approximately 66.4 percent, which rounds to 70 percent.

The bilateral factor

When disabilities affect paired body parts, both arms, both legs, or paired skeletal muscles, the VA applies a bilateral factor. First combine the ratings for the paired extremities using VA math, then add 10 percent of that combined value before combining the result with any other ratings. This extra factor recognizes the additional impact of symmetric impairments beyond what the standard combination formula would otherwise produce.

Example with the bilateral factor

A veteran has a 30 percent left knee rating and a 20 percent right knee rating, both lower extremities. Combining 30 percent and 20 percent first produces 44 percent before rounding. The bilateral factor adds 10 percent of that 44 percent, or 4.4 percent, producing an adjusted bilateral rating of 48.4 percent. That adjusted figure is then combined with any other ratings using the same step-by-step method.

Total Disability based on Individual Unemployability (TDIU)

If your service-connected conditions prevent you from maintaining substantially gainful employment, you may qualify for TDIU, which pays at the 100 percent rate even when your combined schedular rating is lower. The common thresholds are one condition rated at least 60 percent, or a combined rating of 70 percent with at least one condition rated at least 40 percent (38 CFR 4.16(a)). You can also qualify on an extraschedular basis when you do not meet those percentage thresholds but your service-connected disabilities still prevent gainful employment (38 CFR 4.16(b)).

Why the math matters for your compensation

Monthly compensation rates increase with each 10 percent step in your combined rating, and the VA updates its compensation tables periodically to reflect cost-of-living adjustments, so a higher accurately calculated rating has a real and lasting effect on your monthly payment. Confirming that your combined rating, including any bilateral factor you qualify for, was calculated correctly is worth doing before accepting a rating decision at face value.

Next steps with Bill Advantage

All VA tools on Bill Advantage, including the PACT Act Benefits Screener and the VA Benefits Navigator, are permanently free for every tier with no monthly limits. This will never change. Use these tools to check your eligibility and verify your combined rating calculation before filing a new claim or an appeal.

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Bill Advantage is a document literacy tool. Nothing in this article constitutes legal or medical advice.