How Does VA Math Work? Combined Ratings Explained (with Examples)

VA does not add disability ratings together. Under 38 CFR 4.25, a 50% rating and a 30% rating combine to 70%, not 80%, because each new rating applies only to the percentage of the body VA still considers able. This federal formula governs every combined VA disability rating nationwide.

This article explains the federal formula VA uses to combine multiple disability ratings into one number, under 38 CFR 4.25 and 4.26, which applies nationwide. For how a combined rating becomes a monthly payment, see the VA disability benefits hub. To run your own ratings through this exact math, use the free VA disability calculator.

The whole-person theory behind VA math

VA ratings do not stack because 38 CFR 4.25 is built around remaining efficiency, not raw percentage of disability. Every veteran starts at 100% able-bodied. The most severe rating removes that percentage of ability, leaving a smaller pool behind. Each additional rating then applies only to what remains, not to the original whole person. A veteran with a 60% rating keeps 40% of their original efficiency; a further 30% rating removes 30% of that remaining 40%, not 30% of the original 100%. That is why 60% and 30% combine to 72%, not 90%.

"Thus, a person having a 60 percent disability is considered 40 percent efficient. Proceeding from this 40 percent efficiency, the effect of a further 30 percent disability is to leave only 70 percent of the efficiency remaining after consideration of the first disability, or 28 percent efficiency altogether. The individual is thus 72 percent disabled." (38 CFR 4.25)

The formula behind this: combined value = A + B × (100 − A) / 100, where A is the running combined total and B is the next disability in severity order.

Step-by-step worked examples

Three examples show the formula at work. VA sorts every rating from most to least severe, combines them two at a time, and rounds each running total to the nearest whole percent along the way. Only the final number, after every rating has been combined, rounds to the nearest 10. Run your own combination in the VA disability calculator to see the same math applied to your ratings and the 2026 payment tables.

50% and 30%. Combine: 50 + 30 × (100 − 50) / 100 = 65%. That raw 65% ends in 5, so it rounds up. Final combined rating: 70%, not the 80% simple addition would suggest.

60%, 40%, and 20%, the example 38 CFR 4.25 itself uses. Combine 60 and 40: 60 + 40 × 0.40 = 76%. Combine that 76 with 20%: 76 + 20 × 0.24 = 80.8%, which rounds to 81%. Only now does final rounding apply: 81% rounds down to 80%.

60%, 30%, 20%, and 10%. Combine 60 and 30: 60 + 30 × 0.40 = 72%. Combine 72 and 20: 72 + 20 × 0.28 = 77.6%, which rounds to 78%. Combine 78 and 10: 78 + 10 × 0.22 = 80.2%, which rounds to 80%. That value is already an even 10, so the final combined rating stays 80%.

The rounding rule

VA's rounding rule has two parts. Every intermediate step in a multi-condition combination rounds to the nearest whole percent, not the nearest 10, so a running total of 77.6% becomes 78%, not 80%, before the next rating is added. Only the final combined value, once every rating has been combined, converts to the nearest number divisible by 10, and under 38 CFR 4.25(a) a value ending in exactly 5 rounds up. Under 38 CFR 4.25(b), that conversion happens exactly once, as the last step VA performs on a rating decision.

The cliff this creates is real money. Combine 70%, 40%, and 10%: 70 + 40 × 0.30 = 82, then 82 + 10 × 0.18 = 83.8, which rounds to 84%. Since 84 is below the 85 threshold, it rounds down to a final 80% rating. Combine 70% and 50% instead: 70 + 50 × 0.30 = 85% exactly, which rounds up to a final 90% rating. Two combinations one point apart on paper land a full ratings tier apart in the 2026 pay tables, about $260 a month at the veteran-alone rate.

The bilateral factor (38 CFR 4.26)

A separate rule applies to paired limbs. Under 38 CFR 4.26, if a veteran has compensable ratings affecting both arms, both legs, or paired skeletal muscles, VA combines the two ratings normally, then adds 10% of that combined value before folding the result into the rest of the ratings. Derived from the regulation's own four-disability example: two 10% ratings on a bilateral pair combine to 19%; adding 10% of 19 (1.9) gives 20.9%, rounded to 21%. That 21% then enters the severity order as a single disability, not as 19% or 20%.

• Pairing is per limb type. Only same-type pairs qualify: both arms, or both legs. A left-arm rating and a right-leg rating do not combine for the bilateral factor, even though they sit on opposite sides of the body.
• "Arm" and "leg" mean the whole extremity. 38 CFR 4.26(a) defines both terms as the entire upper or lower extremity, not a specific joint or segment. A compensable right thigh rating and a compensable left foot rating qualify as a bilateral leg pair, because both fall within the lower extremity.
• Four affected limbs. When both arms and both legs are all independently rated, 38 CFR 4.26(b) combines all four ratings first, in severity order, and applies the 10% add-on once to that combined value, not twice.
• The 2023 favorable-to-veteran exception. Since an April 2023 amendment, 38 CFR 4.26(d) requires VA to also calculate the rating without grouping the bilateral pair, and to use whichever version, with or without the factor, produces the higher rating.

Why VA math exists

VA's combined-ratings method reflects a policy judgment: disability is not perfectly additive. A veteran who has already lost 60% of their functional capacity is not equally impaired by an additional 30%-rated condition as someone starting from zero, because there is less "whole person" left to lose. Capping every combined rating at 100%, regardless of how many conditions a veteran has, follows the same logic; nobody can be more than totally disabled. VA has applied some version of this efficiency-based model for decades, carried forward through revisions of the rating schedule, because it produces one consistent result no matter how many ratings, or in what order, they are combined.

Common misconceptions

Three mistakes explain most of the confusion around combined ratings.

• "My ratings should add up." They never do once more than one rating is involved. The 38 CFR 4.25 formula always produces a result equal to or lower than straight addition.
• "Every step rounds to the nearest 10." Only the final value does. Intermediate combinations round to the nearest whole percent and carry that exact figure into the next step.
• "The bilateral factor always helps." It usually raises the rating, but the 4.26(d) exception exists because the bilateral calculation can occasionally produce a lower result than treating the ratings as unrelated; VA must use whichever version pays more.
• "A high combined rating means TDIU." Reaching 100% by combining ratings and qualifying for Total Disability based on Individual Unemployability are different paths. TDIU pays the 100% rate to veterans below a 100% schedular rating who meet the 38 CFR 4.16(a) thresholds and cannot sustain substantially gainful work.

What if the math looks wrong on your decision?

A combined rating that does not match a veteran's own math is not always an error; the formula above regularly produces results that look wrong at first glance. But VA does make genuine mistakes, such as missing a bilateral pairing or rounding at the wrong step. Combining the same ratings in a different order is not one of them, because the formula gives the same combined value either way. A decision that appears to miscalculate the combined value fits a Higher-Level Review under 38 CFR 3.2601, where an experienced adjudicator who did not take part in the prior decision reviews the same record with no deference to it, or an appeal to the Board of Veterans' Appeals under 38 CFR 3.2500(a)(1)(ii). A Supplemental Claim is a poor fit for a pure math error: under 38 CFR 3.2501 it needs new and relevant evidence, and without it VA only issues a finding that there was insufficient evidence to readjudicate the claim. The how to appeal a VA rating spoke covers which lane fits a suspected math error.

This article explains VA's published combined-ratings formula for general informational purposes and is not legal advice. It is not a substitute for review by an accredited VA representative or a licensed attorney. RecordingLaw.com is not affiliated with, endorsed by, or sponsored by the U.S. Department of Veterans Affairs. Filing an initial VA disability claim yourself is always free at va.gov. Information verified as of July 2026 against the eCFR and va.gov; the underlying regulations can change, as 38 CFR 4.26 did in 2023.

Frequently Asked Questions

How does VA math work?

VA combines multiple disability ratings using a whole-person formula under 38 CFR 4.25, not addition. Each new rating applies only to the percentage of the body VA still considers able, so a 50% and a 30% rating combine to a raw 65%, which rounds up to a final 70%.

Why is my VA combined rating not adding up?

Because VA ratings are never simply added. The formula in 38 CFR 4.25 always produces a number equal to or lower than straight addition, and the running total converts to the nearest 10% only once, as the very last step, per 38 CFR 4.25(b).

What is the bilateral factor in VA disability?

A 10% bonus added under 38 CFR 4.26 when a veteran has compensable ratings affecting both arms or both legs. The two ratings combine normally, then VA adds an extra 10% of that combined value before folding the result into the rest of the ratings.

Why did my VA rating round down instead of up?

The final combined value rounds to the nearest 10%, and only values ending in exactly 5 round up, under 38 CFR 4.25(a). A raw combined value of 84% rounds down to 80%, while 85% rounds up to 90%.

Why don't two 50% ratings equal 100%?

Because the second 50% rating applies only to the 50% of the body still considered able after the first rating, not to the original whole person. Two 50% ratings combine to a raw 75%, which rounds up to a final 80%.

Can VA combined math alone reach exactly 100%?

Yes, if the raw combined value reaches 95% or higher before final rounding, since 95 through 100 round up to 100%. Short of that, a veteran below a 100% schedular combined rating may still qualify for TDIU, which pays at the 100% rate.