What Is VA Math?
VA Math is the method the Department of Veterans Affairs uses to calculate a combined disability rating when a veteran has more than one service-connected condition. Rather than adding percentages together, the VA applies each rating sequentially to the remaining "healthy" portion of your body. This formula is codified in federal regulation at 38 CFR § 4.25.
Why Doesn't the VA Just Add Ratings?
The logic is straightforward: a person can never be more than 100% disabled. If a veteran has a 60% rating for one condition and a 50% rating for another, simple addition would give 110%, which is impossible. Instead, the VA considers how much of the whole person remains unaffected after each disability is accounted for. Each subsequent rating only applies to the remaining healthy percentage.
How the Calculation Works
The VA always starts with your highest-rated disability and works down. In our example, the 50% rating is applied first, leaving 50% of the body healthy. The 30% rating is then applied to that remaining 50%, which takes away another 15 percentage points (30% of 50). The total combined value is 65%, which the VA rounds to the nearest 10% for your official rating: 70%.
What About More Than Two Ratings?
The same process continues for each additional disability. If you also had a 20% rating, you would apply 20% to the remaining 35% from the example above. That gives 7 more points (20% of 35), bringing the combined value to 72%, which rounds to 70%. With many conditions, the math gets complicated quickly, which is why using a VA disability calculator saves time and prevents errors.
Understanding VA Math helps veterans set realistic expectations during the claims process. Knowing how ratings combine helps you understand why adding one more condition may not increase your overall rating as much as you expect, and why the final rounded percentage is what determines your monthly compensation amount.