How VA Math Works 2026 — Combined Disability Rating Guide

If you have multiple service-connected disabilities, the VA does not simply add your ratings together. A 50% rating and a 30% rating do not give you 80%. Instead, the VA uses a specific formula codified in 38 CFR 4.25 to produce a combined rating that is almost always lower than the sum of its parts. Veterans call this formula "VA math," and understanding it is one of the most important things you can do before filing a claim or an appeal.

This guide walks through the exact formula, shows worked examples with two, three, and four ratings, explains the bilateral factor, clears up common misconceptions, and covers the rounding rules that can make or break your compensation tier. If you want to skip the math entirely, our VA disability calculator will do all of this for you in seconds.

Why the VA Doesn't Just Add Ratings Together

The VA's rating system is built on something called the whole person theory. The core idea is straightforward: every veteran starts at 100% healthy, and each disability takes away a portion of what remains. You do not start at zero and accumulate disability. You start whole and lose capacity.

This matters because the VA is measuring the percentage of your overall functional ability that each condition impairs. A 50% rating means half of your functional capacity is gone. A second condition cannot also impair capacity that is already gone. It can only impair what is left.

Here is a quick example to illustrate. Suppose you have two rated conditions: 50% for a lumbar spine condition and 30% for a shoulder injury. Simple addition says that is 80%. But under VA math, the answer is different:

That 10-percentage-point gap between 80% and 70% translates to a significant difference in monthly compensation. At the 80% rate for a single veteran with no dependents, you would receive $1,995.01 per month. At 70%, it is $1,808.45. That is a difference of $186.56 every month, or $2,238.72 per year. Understanding VA math helps you set realistic expectations and plan your claims strategically. You can look up exact payment amounts for every rating on our VA disability rates table.

The VA Math Formula Explained

The VA math formula applies each disability rating sequentially to the remaining healthy percentage of your body. Here is the step-by-step process:

1. Start with 100% — this represents your whole, healthy body before any disabilities.
2. Apply the highest rating first. Subtract it from 100 to get your remaining healthy percentage. If your highest rating is 50%, you have 50% remaining.
3. Apply the next highest rating to what is left. Multiply the second rating by the remaining percentage and subtract the result. If the next rating is 30%, take 30% of 50 = 15. Your new remaining healthy percentage is 50 - 15 = 35%.
4. Repeat for each additional rating, always applying the next rating to the current remaining healthy percentage.
5. Your combined disability is 100 minus the final remaining percentage.
6. Round the final result to the nearest 10%.

Expressed as a formula, the combined rating for multiple disabilities R1, R2, R3, and so on is:

The order you multiply the factors does not change the result mathematically. The VA sorts from highest to lowest by convention, but the final combined number is the same regardless of order. What matters is the formula itself.

Worked Example — Two Ratings

Let us walk through the most common scenario: combining two disability ratings. Suppose you have a 50% rating for a service-connected condition and a 30% rating for a second condition.

At a 70% combined rating, a single veteran with no dependents receives $1,808.45 per month in 2026. You can verify this and model different scenarios with our VA disability rating calculator.

Using the formula: Combined = 1 - (1 - 0.50)(1 - 0.30) = 1 - (0.50 × 0.70) = 1 - 0.35 = 0.65 = 65%. Same result.

Worked Example — Three Ratings

Now let us add a third condition. You have ratings of 50%, 30%, and 20%. If the VA simply added these, you would have 100%. VA math tells a different story.

Notice something important: adding a third condition at 20% moved the exact combined value from 65% to 72%, but the rounded result stayed at 70%. Your monthly compensation does not change. This is one of the most frustrating aspects of VA math for veterans. You proved a new service-connected condition, went through the claims process, and your paycheck did not budge.

However, that 72% is now much closer to rounding up to 80%. One more condition at even 10% could push you over the threshold. Understanding where you stand in the rounding is essential for planning future claims. For strategies on building your rating, see our guide on how to increase your VA rating to 100%.

Worked Example — Four Ratings (Getting to 90%+)

Here is a more complex scenario with four rated conditions: 70%, 50%, 30%, and 10%. This is common for veterans with several years of service and multiple injuries.

With four conditions that add up to 160% through simple math, VA math produces 90%. That is a significant gap, but 90% still represents substantial compensation. And at 90.55%, you are tantalizingly close to the 95% threshold that would round up to 100%. One additional condition rated at 50% or higher would push the exact combined value past 95%.

If reaching 100% schedular is not realistic through additional ratings, you may qualify for Total Disability Individual Unemployability (TDIU), which pays at the 100% rate if your disabilities prevent you from holding substantially gainful employment.

The Bilateral Factor Explained

The bilateral factor is an adjustment the VA makes when you have disabilities affecting paired extremities — that is, both arms, both legs, both knees, both shoulders, or any other matching pair. The logic is that losing function on both sides of your body is more debilitating than losing the same total function on just one side.

Here is how the bilateral factor works:

1. Identify bilateral pairs. Find conditions that affect both sides of the same body part (e.g., left knee and right knee).
2. Combine the bilateral ratings using the standard VA math formula.
3. Add 10% of the combined bilateral value back to the result. This is the bilateral factor.
4. Use the adjusted bilateral subtotal when combining with your remaining non-bilateral conditions.

The bilateral factor is modest — it adds 10% of the combined bilateral rating, not 10 percentage points. In the example above, it adds 2.8 points, not 10. But in a system where a single percentage point can determine whether you round up or down, even small additions matter. Use our VA disability calculator to model bilateral conditions and see the exact impact.

Common VA Math Misconceptions

VA math is counterintuitive, and that leads to persistent myths. Here are the three most common.

"I should have 100% but the VA only gave me 90%." This is often said by veterans who add their individual ratings and get well over 100%. But VA math almost never produces a combined rating equal to the sum. To reach 100% schedular, you typically need either a single condition rated at 100% or a combination of very high ratings whose VA math result hits 95% or above. It is mathematically difficult. For example, even 70% + 50% + 30% + 10% only produces 90.55%.

"Adding a 10% rating should increase my payment." Not necessarily. A 10% rating applies to your remaining healthy percentage, which shrinks as your combined rating grows. If your existing combined rating is 72%, you only have 28% remaining. Ten percent of 28 is 2.8 points, bringing you to 74.8%, which still rounds to 70%. Your compensation does not change. This is why veterans with high existing ratings often see no payment increase from small additional ratings.

"The bilateral factor doubles my rating." It does not. The bilateral factor adds 10% of the combined bilateral value, not 10 full percentage points and certainly not a doubling. For two conditions combining to 28%, the bilateral factor adds only 2.8 points. It is a meaningful but modest adjustment.

VA Math Rounding Rules

Rounding is where VA math can either help or hurt you the most. Here are the rules that govern it:

The .5 rule: When the final combined percentage ends in .5 or higher, it rounds up. A combined 65% rounds to 70%. A combined 74% rounds to 70%. A combined 75% rounds to 80%. That single digit makes an enormous difference in monthly pay.

When rounding happens: Per 38 CFR 4.25 and the combined ratings table, intermediate values are not rounded between combination steps. The VA calculates the exact combined value across all disabilities first, then rounds the final result to the nearest 10%. This means a combined value of 72.4% stays at 72.4% through the entire calculation and only becomes 70% at the very end.

Rounding thresholds that matter most: The biggest jumps in compensation happen at the higher tiers. The difference between 90% and 100% is the largest single jump in the pay table. A veteran at 94% rounds to 90%, while a veteran at 95% rounds to 100%. That one-point gap is worth well over $1,000 per month. At 100% with no dependents, you receive $3,737.85 per month compared to $2,241.91 at 90% — a difference of $1,495.94 monthly.

What Rating Combinations Get You to 100%?

Reaching a 100% combined rating through VA math requires an exact combined value of 95% or higher before rounding. Here are common paths that get you there:

Rating Combination	Exact Combined	Rounds To
90% + 70%	97%	100%
90% + 60%	96%	100%
80% + 80%	96%	100%
80% + 70% + 50%	97%	100%
70% + 70% + 60%	96.4%	100%
90% + 50% + 10%	95.5%	100%
70% + 60% + 50% + 30%	95.8%	100%

And here are some combinations that fall just short:

Rating Combination	Exact Combined	Rounds To
90% + 50%	95%	100%
90% + 40%	94%	90%
80% + 70%	94%	90%
70% + 60% + 50%	94%	90%

Notice how 90% + 50% just barely makes it to 95% and rounds up to 100%, while 90% + 40% falls one point short at 94% and rounds down to 90%. That one-point gap represents nearly $1,500 per month in compensation. If you are close to one of these thresholds, check whether you have any undiagnosed or unfiled conditions that could push you over. Our VA disability calculator lets you add and remove ratings to see exactly where you land.

Frequently Asked Questions

What is VA Math?
VA math is the colloquial term for the method the VA uses to combine multiple disability ratings into a single combined rating. Defined in 38 CFR 4.25, it applies each rating to the remaining healthy percentage of the body rather than adding ratings together. The formula is Combined = 1 - (1 - R1)(1 - R2)(1 - R3)..., with the final result rounded to the nearest 10%.

What does 50% + 30% equal in VA math?
It equals a combined rating of 70%. The exact math: start at 100%, apply 50% (leaving 50% healthy), then apply 30% to the remaining 50% (30% of 50 = 15). Combined disability = 65%, which rounds to 70%. You can verify this instantly with our VA disability calculator.

How does the bilateral factor work?
The bilateral factor applies when you have disabilities affecting paired extremities, such as both knees, both ankles, or both shoulders. The VA combines those bilateral ratings first, then adds 10% of the combined bilateral value back to the result. This adjusted bilateral subtotal is then combined with your non-bilateral ratings using the standard formula.

Why did my rating not increase when I added a 10%?
Because a 10% rating applies to your remaining healthy percentage, which shrinks as your combined rating grows. If you are already at 72% combined, you only have 28% remaining. Ten percent of 28 is 2.8 points, putting you at 74.8%, which still rounds to 70%. The payment does not change until the rounded value moves to a new tier.

What combinations equal 100% VA disability?
Your exact combined value must reach 95% or higher to round to 100%. Common paths include 90% + 70% (97%), 80% + 80% (96%), and 90% + 50% (95%). If your conditions prevent you from working but your combined rating does not reach 100%, you may qualify for TDIU, which pays at the 100% rate.