The Playbook › Step 1 of 7: Know the rules
VA math is the way VA turns several ratings into one. VA does not add your ratings together. It combines them, and the result is almost always lower than the sum. A veteran with a 50% rating and a 30% rating is not 80% disabled in VA’s eyes. They are 70%.
VA math is odd but it is consistent, and once you understand it you can see exactly what you would need to reach the next pay level.
The short version
- VA treats you as a “whole person” who starts at 100% efficiency.
- Each rating takes a percentage of what is left, not of the original 100.
- Ratings are combined from highest to lowest. Each step is rounded to a whole number, and the final value is rounded to the nearest 10.
- A combined value ending in 5 rounds up. 65 becomes 70. 64 becomes 60.
- Disabilities affecting both arms or both legs get a 10% bilateral factor boost.
On this page
The whole-person idea
Picture a person who is 100% able. A 50% disability leaves them 50% able. A second disability of 30% does not take 30 points off the original 100. It takes 30% of the remaining 50, which is 15. So:
- Start: 100% able
- After the 50% rating: 50% able
- After the 30% rating: 50 minus 15 = 35% able
- Combined disability: 100 minus 35 = 65%, which rounds to 70%
VA math, step by step
- List your ratings from highest to lowest.
- Subtract the highest from 100. That is your remaining ability.
- Multiply the remaining ability by the next rating. Subtract the result.
- Round to the nearest whole number. A half rounds up.
- Repeat steps 3 and 4 for each rating.
- Subtract what is left from 100. That is your combined value.
- Round to the nearest 10. Values ending in 5 or more round up.
Step 4 matters. VA does not carry decimals from one rating to the next. It reads each step from its Combined Ratings Table, which only contains whole numbers. With several ratings, those small roundings can be the difference between 94 and 95, and so between 90% and 100%.
VA math worked examples
| Ratings | Combined value | Final rating |
|---|---|---|
| 50%, 30% | 65 | 70% |
| 50%, 30%, 10% | 69 | 70% |
| 70%, 50% | 85 | 90% |
| 70%, 30%, 20% | 83 | 80% |
| 40%, 20%, 10%, 10% | 61 | 60% |
| 90%, 50% | 95 | 100% |
Look at the fourth row. Three ratings that add up to 120 produce an 80% combined rating. That surprises almost everyone the first time.
Why rounding decides your pay
Because the final number rounds to the nearest 10, a combined value of 64 pays at 60% and a value of 65 pays at 70%. In 2026 that single point is worth about $373 a month for a veteran with no dependents. If you are sitting just under a rounding line, one more 10% rating can move you up a full tier. The calculator shows how close you are.
Why 100% is so hard to reach
Each new rating applies to a smaller and smaller remainder. A veteran at 90% has only 10 points of “ability” left on paper, so a new 50% rating adds just 5 points. That gets them to 95, which rounds to 100. A new 30% rating adds only 3 points, and they stay at 90%.
This is why many veterans with serious disabilities plateau at 80% or 90%. If your conditions keep you from holding a steady job, TDIU pays at the 100% rate without a 100% combined rating.
The bilateral factor
If you have rated disabilities on both arms, both legs, or paired skeletal muscles, VA gives you a boost:
- Combine the ratings for those paired limbs.
- Add 10% of that combined value to it.
- Treat the result as one rating and combine it with everything else.
Example. A 30% right knee and a 20% left knee combine to 44. Ten percent of 44 is 4.4, giving 48.4, which VA rounds to 48 before combining it with anything else. On their own, the two knees come to 50% instead of 40%.
The factor applies to one condition on each side. It does not need to be the same joint. A right knee and a left ankle qualify.
What this means for your claim
- Claim everything that is legitimately service connected. Small ratings matter most when you are near a rounding line.
- Look for secondary conditions. They are often the most realistic way to move up. See secondary conditions.
- An increase on your highest-rated condition usually moves the combined number more than a new low rating.
- Do not assume you are stuck at 90%. Check TDIU.
Check your own numbers
The VA disability calculator does all of this for you, including the bilateral factor, dependents, and a roadmap showing what it would take to reach each higher rating.
Free printable checklist. Everything to gather before you file, what to bring to your C&P exam, and what to check in your decision, on two pages.
Last reviewed October 2026. This guide is general educational information, not legal or medical advice, and this site is not affiliated with the Department of Veterans Affairs. Rules and rates change. Confirm details on VA.gov or with an accredited representative. See our disclaimer and editorial policy.