VA disability combined ratings calculator

Quick answer: VA combines ratings with the whole-person method: sort the ratings from highest to lowest, apply each one to whatever efficiency remains, then round the final figure to the nearest 10. That is why 50% plus 50% is 80%, not 100%. Try it below.

How VA math works: the whole-person method

VA ratings measure how much a service-connected disability reduces the body's overall efficiency. A veteran starts at 100% efficiency. A 30% rating means the disability removes 30% of that efficiency, leaving 70%. Here is the part that surprises everyone: the next rating does not apply to the original 100%. It applies only to the efficiency that remains. That rule lives in 38 CFR 4.25, and VA calls it the whole-person theory.

The formula is straightforward once you see it. Sort the individual ratings from highest to lowest. Starting with 100% efficiency, each rating removes its percentage of what is left:

Combined rating = 1 minus (1 minus r1) times (1 minus r2) times (1 minus r3) ...

Take 50% and 30%. The 50% rating leaves 50% efficiency. The 30% rating removes 30% of the remaining 50, which is 15, so the running total is 65%. Round to the nearest 10 and the combined rating is 70%. Dana and Marcus walked through exactly this walkthrough in The Claim Game podcast, and their rule of thumb still works: every new rating is worth less than its face value because it only bites the leftover slice.

Why 50% plus 50% is not 100%

This is the single most common question veterans ask, and the single most tested idea on combined ratings. Adding 50 plus 50 gets you 100 in grade school math. In VA math, the second 50% applies to the 50% efficiency the veteran still has. Half of 50 is 25, so the raw combined figure is 75. Rounded to the nearest 10, that is 80%. The veteran is paid at 80%, not 100%.

Notice what happens with a bigger set, like 40% + 30% + 20% + 10%. Efficiency multiplies down: 0.60 times 0.70 times 0.80 times 0.90 = 0.3024, so the combined figure is 69.76%, rounded to 70%. The simple sum would say 100%. The whole-person method says 70%. Both the calculator above and the official VA disability ratings calculator on va.gov agree on that answer, which is how you know the formula is implemented correctly.

The bilateral factor, without the mystery

38 CFR 4.26 adds a bonus when disabilities affect both arms, both legs, or paired muscle groups. VA combines the bilateral disabilities the usual way, then adds 10% of that combined value as the bilateral factor, and combines the adjusted figure with the remaining disabilities. The bonus is added, not combined, and it reflects a real policy judgment: paired-limb disabilities hurt overall function more than the same ratings on one side.

Example: bilateral 30% and 20%. Combined normally that is 44%. The bilateral factor is 10% of 44, which is 4.4, giving an adjusted bilateral figure of 48.4%. That 48.4% then combines with everything else as a single figure. Two cautions keep this accurate. First, the factor only applies to true paired-limb or paired-muscle disabilities, not to any two ratings you feel like pairing. Second, a single marked disability gets no factor at all, which is why the calculator above warns you if only one box is ticked.

Common mistakes, and what the exam tests

• Adding the ratings together. VA math never sums ratings. If an exam choice or a buddy's advice just adds them, it is wrong.
• Rounding the intermediate steps. Only the final combined figure is rounded to the nearest 10. Keep the decimals until the end, which the calculator's step table does for you.
• Assuming order matters. The regulation lists ratings in descending order, but multiplication commutes: the same ratings give the same combined figure in any order. The convention is about readability, not arithmetic.
• Forgetting the bilateral factor. A veteran with bilateral disabilities and a straightforward combined figure may be underrated if the factor was never applied.
• Thinking 0% ratings are pointless. A 0% rating changes nothing in the math, but it establishes service connection, which supports future increases and secondary claims.
• Confusing the combined rating with the pay rate. The combined rating determines which compensation level applies, but the dollar amounts are set separately. 38 U.S.C. 1114 lays out the wartime disability compensation rate tables, and VA publishes the current monthly amounts at va.gov.

Effective dates: when your combined rating starts

The combined rating is only half the story. The other half is the effective date: the day VA starts paying at that level. The general rules are in 38 CFR 3.400. As a rule of thumb, a direct service-connection grant is effective the day after separation or the date the claim was received, whichever is later, while an increase is generally effective the date of the claim or the date the increase became factually ascertainable, whichever is later.

Why this matters for the calculator: a veteran who uses this tool after a new rating decision should compare the result to the decision letter, because effective dates can split the timeline. A new 30% grant effective in March and a 20% increase effective in June can produce different combined ratings for different periods, and VA may issue staged ratings that pay different levels across those periods. The calculator gives you the combined figure for one set of ratings at one moment in time. It does not time-travel.