What Is VA Math?
"VA math" refers to the method the VA uses to combine multiple disability ratings into a single combined rating. Instead of simply adding your ratings together, the VA uses the "whole person" theory defined in 38 CFR § 4.25.
The key concept: each disability rating is applied to your remaining ability, not your total ability. A veteran starts at 100% able-bodied, and each disability reduces a percentage of what remains.
Step-by-Step Example
| Individual ratings | Table I combinations | Final rating |
|---|---|---|
| 50%, 30% | 65 | 70% |
| 50%, 30%, 10% | 65, then 69 | 70% |
| 70%, 50%, 20%, 10% | 85, then 88, then 89 | 90% |
| 60%, 30%, 10% | 72, then 75 | 80% |
Let's say you have three disability ratings: 50%, 30%, and 10%.
Simple addition would give you 90%, but VA math works differently:
- Start with the highest rating: 50%. You now have 50% remaining ability.
- Apply 30% to the remaining 50%: 30% × 50% = 15%. Combined value: 50% + 15% = 65%. Remaining ability: 35%.
- Apply 10% to the remaining 35%: 10% × 35% = 3.5%. Combined value before table rounding: 68.5%. Table I records this as 69%, which is the value carried to any next combination.
- Round to nearest 10%: 69% rounds to 70%.
Your combined VA rating would be 70%, not 90%.
Try the calculator to see how VA math applies to your specific ratings.
The Bilateral Factor
The bilateral factor (38 CFR § 4.26) provides a small bonus when you have disabilities affecting both sides of the body — for example, both knees, both arms, or both legs.
How it works:
- Combine the bilateral disabilities using VA math.
- Add 10% of that combined value to itself.
- Round to a whole number and treat the result as one disability in the overall combination.
The factor applies only when each side has a compensable (10% or higher) rating. When both arms and both legs are affected, all four are combined together and get one factor.
Under § 4.26(d), VA excludes one or more disabilities from the bilateral calculation if separate combination gives a higher final evaluation. Our calculator compares valid paired groups and separate combinations to apply this favorable exception. It is an estimate; confirm the conditions and extremity designations against your VA decision.
Example: Left knee 20% + Right knee 10%. Combined bilateral: 20% + (10% × 80%) = 28%. Bilateral factor: 28% × 10% = 2.8%. Adjusted value: 28% + 2.8% = 30.8%, which VA uses as 31% in the overall combination (38 CFR § 4.26 treats the adjusted value as one whole-number rating).
Rounding Rules
Use the whole-number Table I result at each combination, in descending order. Only after all combinations, round to the nearest 10%; values ending in 5 round up. For example, 60 and 30 combine to 72; 72 and 10 combine to 75, giving 80%. Keeping fractional intermediates instead would incorrectly give 74.8 and 70%. Around the 70%/80% boundary:
- 65% through 74% rounds to 70%
- 75% through 84% rounds to 80%
This rounding can make a significant difference in your monthly payment, especially at higher rating levels.
Why VA Math Matters
Understanding VA math helps you set realistic expectations for your combined rating and monthly compensation. It also helps you understand why pursuing additional claims may or may not significantly change your combined rating.
A rounded 90% rating does not tell you the underlying combined value. A Table I value of 90 combined with another 10 stays in the 90% tier, but a value of 94 combined with 10 becomes 95 and rounds to 100%. Recalculate from all individual ratings rather than treating the rounded tier as an individual disability.
Last updated / Correction — October 21, 2026: Examples now use the whole-number values from VA's Table I (for example, 69, not 68.5) and include a 60% + 30% + 10% example.
This content is for informational purposes only and does not constitute legal or medical advice. For personalized guidance, consult a VA-accredited VSO, attorney, or claims agent.