How VA math works: the "whole person" concept
The single most confusing thing about VA disability is that ratings don't add. An 80% rating plus a 40% rating is not 120% — you can't be more than 100% of a whole person. Under 38 CFR §4.25, the VA treats you as starting from 100% efficiency, and each disability takes its percentage out of what's left. Once an 80% rating has claimed 80 points, only 20% efficiency remains — so a 40% rating takes 40% of that remaining 20, which is 8 points, not 40. That lands you at 88.
The procedure, exactly as the VA's Combined Ratings Table implements it: sort your ratings from largest to smallest, combine them one at a time against the remainder (rounding each step to the nearest whole number — the table's entries are whole numbers), and then convert the final raw value to the nearest 10. VA.gov states the rounding rule plainly: raw values ending in 1–4 round down, and 5–9 round up. So a raw 88 becomes an official 90%, while a raw 84 becomes an official 80%. This calculator shows you both numbers, because the raw value tells you how close you are to the next tier.
The formula
A is your running combined value so far (start with your single largest rating) and B is the next rating being folded in. Each step is rounded to the nearest whole number, matching the VA's table. After the last rating, the raw result is rounded to the nearest 10 — with values ending in 5 rounding up — to produce your official combined rating. Monthly compensation then comes from the VA's published rate table, effective December 1, 2025.
Worked example
A veteran has three ratings: 60%, 40%, and 20% — the exact example printed in 38 CFR §4.25. On paper they "add" to 120. The VA math:
Step 1: Start at 60.
Step 2: Combine 40% → 60 + 40% of the remaining 40 = 60 + 16 = 76.
Step 3: Combine 20% → 76 + 20% of the remaining 24 = 76 + 4.8 = 80.8, which the table carries as 81.
Raw combined value: 81. Official rating: 80% (81 rounds down). Monthly compensation for a veteran alone in 2026: $2,102.15 — $25,225.80 a year, tax-free. And the raw 81 is just 4 points below 85, where the rating would round up to 90% instead.
The rounding cliff: why raw 84 and raw 85 are different worlds
Because the official rating rounds to the nearest 10, a single raw point at the boundary is worth an entire tier. A raw 84 rounds down to 80% — $2,102.15 a month in 2026. A raw 85 rounds up to 90% — $2,362.30 a month. That one raw point is worth $260.15 every month, $3,121.80 every year, indefinitely. The cliff at the top is even steeper: a raw 94 stays at 90%, while a raw 95 rounds up to 100% — and 100% pays $3,938.58, a jump of $1,576.28 a month ($18,915.36 a year) over 90%.
This is why claims for even a 10% increase genuinely matter. A veteran sitting at a raw 84 who wins service connection for one more 10% condition moves to a raw 86 (84 + 10% of the remaining 16 = 85.6, carried as 86) — crossing the boundary and jumping from 80% to 90%. The same 10% rating awarded to a veteran at a raw 78 changes nothing (78 → 80, still 80%). The calculator's "distance to next tier" row exists precisely so you can see which situation you're in before deciding whether an increase claim or a new secondary claim is worth pursuing.
The bilateral factor (38 CFR §4.26)
When disabilities affect paired limbs — both arms, both legs, or paired skeletal muscles — 38 CFR §4.26 gives a small but real bonus: the ratings for the two sides are combined first, then 10% of that combined value is added (added, not combined), and the result is treated as a single disability when it joins your other ratings. This calculator implements it — enter the pair in the two bilateral fields above.
The regulation's own example: a veteran with 60%, 20%, and a bilateral pair of 10% and 10%. The pair combines to 19; adding 10% of 19 (1.9) gives 20.9, treated as 21. The sequence 60, 21, 20 then combines to 68, then 74 — an official 70%. In that particular case the factor happens not to change the outcome (running the same four ratings without it also reaches a raw 74). But it absolutely can: two 40% knees combined alone give a raw 64 — an official 60% — while the bilateral factor lifts them to a raw 70 (64 + 6.4 = 70.4, carried as 70), an official 70%. That's $1,808.45 a month instead of $1,435.02 — $373.43 a month from one regulation most veterans have never heard of.
What this calculator doesn't cover
Dependents. The results here are for a veteran alone. At a combined rating of 30% or higher, the VA pays more if you have a dependent spouse, children, or dependent parents — at 10% and 20% dependents don't change the amount. Your rating is identical either way; only the check changes. The exact amounts are on the VA's rate page.
TDIU. If your service-connected conditions keep you from holding substantially gainful employment, Total Disability based on Individual Unemployability can pay you at the 100% rate even though your combined rating is lower — typically available when one disability is rated 60%+, or the combined rating is 70%+ with at least one condition at 40%+. A veteran with a combined 70% who can't work may draw $3,938.58 a month instead of $1,808.45. No percentage calculator can tell you whether you qualify; it depends on your work history and the evidence, not the arithmetic.
SMC. Special Monthly Compensation pays above the 100% rate for specific severe circumstances — loss or loss of use of limbs, need for aid and attendance, and others. It's assigned by the VA on top of, or instead of, the schedular rates and is outside this calculator's scope.
Two more things worth real money. First, VA disability compensation is completely tax-free — it never appears on your return, which makes each dollar worth more than a dollar of wages (run your salary through the income tax calculator to see what taxable income loses to withholding). Second, receiving VA disability compensation at any rating — 10% counts — makes you exempt from the VA loan funding fee, which on a typical zero-down purchase is thousands of dollars waived; the VA loan calculator models the exemption directly.