Veterans often find that VA disability math is more complicated than expected. You’ve probably noticed this when you received your rating decision and saw that your combined percentage doesn’t match the total of your individual ratings. The VA uses a unique formula, based on the VA combined ratings table and the “whole person” concept, to calculate your overall disability rating. When you understand this system, you can verify your rating is correct and advocate more effectively for the benefits you’ve earned.

Why Doesn’t the VA Just Add Up Your Ratings?

The VA doesn’t add ratings because it uses the “whole person” approach outlined in 38 CFR §4.25. Instead of simple addition, the VA applies each new rating to your remaining “efficiency,” preventing totals from ever exceeding 100%.

Here’s the concept: you start at 100% efficient. Your highest-rated condition reduces that efficiency, and every additional rating is applied to what’s left. This prevents your total from ever exceeding 100%, regardless of the number of conditions you have.

How to Calculate VA Disability Ratings Yourself

The VA follows this method when they calculate your combined rating. You can use the same steps to verify their work or better understand your rating decision.

  1. List your conditions from highest to lowest rating
  2. Start with 100% efficiency
  3. Apply the highest rating first by subtracting it from 100%
  4. For each next rating, apply that percentage as a reduction of the “remaining healthy percentage” (not simply subtracting it). That is, multiply the new rating by your current remaining efficiency and subtract the result from your current efficiency.
  5. Continue to apply each rating in order If your ratings include paired extremity conditions (arms, legs, or paired joints), add the bilateral factor: calculate 10% of the combined value for those extremities, then add this to your combined percentage before adding further ratings or rounding.
  6. If you have more than two ratings, continue combining them. Each time you bring in another rating, combine your latest result (unrounded) with the next rating using the same process, or use the ratings table again to combine.
  7. Round your final combined value to the nearest 10%; values ending in 1–4 round down, 5–9 round up.

How Does VA Math Work in Practice?

Example 1: Three Conditions

Let’s say you have 50% for your back, 30% for sleep apnea, and 10% for tinnitus.

  • Start at 100%
  • Subtract 50% → 50% remains
  • 30% of 50% = 15%. Subtract → 35% remains
  • 10% of 35% = 3.5%. Subtract → 31.5% remains
  • Total disabled = 100% – 31.5% = 68.5%, which rounds to a 70% combined rating

Example 2: Secondary Conditions Included

Now imagine you have 40% for PTSD, 20% for a knee injury, and 10% for migraines secondary to PTSD.

  • 40% of 100% = 40%. Remaining: 60%
  • 20% of 60% = 12%. Remaining: 48%
  • 10% of 48% = 4.8%. Remaining: 43.2%
  • Total disabled = 100% – 43.2% = 56.8%, rounded to a 60% combined rating

Example 3: The Bilateral Factor Applied

You have a 30% injury to your right knee and a 20% injury to your left.

  • 30% of 100% = 30%. Remaining: 70%
  • 20% of 70% = 14%. Combined = 44%
  • Bilateral factor = 10% of 44% = 4.4%. Add this 4.4% to 44% to get 48.4% (not to 100% – 44%)
  • Add 10% for tinnitus: 10% of (100% – 48.4% = 51.6%) = 5.16%.
  • Subtract from 51.6% → 46.44% efficiency, total disability 53.56%.
  • Round to nearest 10% = 50%

The bilateral factor applies when health conditions affect both sides of paired extremities (arms, legs, or paired joints). It adds 10% of the combined value of both conditions to the total before rounding.

What Is the VA Combined Ratings Table?

The VA combined ratings table is the official tool the VA uses to determine your overall disability rating. It’s built around the same math discussed above and is part of federal regulations (38 CFR §4.25).

How to use the table to verify your rating:

  1. Locate your highest rating across the top row.
  2. Find your next highest rating down the left column.
  3. The point where they intersect shows your new combined rating.
  4. If you have more than two ratings, repeat the process: take your combined value and combine it again with your next highest individual rating using the table.
Next ↓ / First → 10 20 30 40 50 60 70 80 90
10 19 28 37 46 55 64 73 82 91
20 28 36 44 52 60 68 76 84 92
30 37 44 51 58 65 72 79 86 93
40 46 52 58 64 70 76 82 88 94
50 55 60 65 70 75 80 85 90 95
60 64 68 72 76 80 84 88 92 96

How Are VA Secondary Conditions Calculated?

VA secondary conditions are calculated exactly like primary conditions once they’re approved, and the process is identical to the calculation of primary disability benefits.

A secondary condition is one that develops as a result of a service-connected disability. Common examples include:

  • Sciatica caused by a service-connected back injury
  • Depression resulting from chronic pain
  • Migraines stemming from PTSD
  • Sleep disorders secondary to mental health conditions

Once the VA grants service connection for a secondary condition, it assigns a percentage, just like any other. You then include it in your list and apply the same VA disability math using the VA combined ratings table or the step-by-step method.

How the VA Calculates Secondary Conditions

VA secondary conditions are calculated exactly like primary conditions once they’re approved. The process is identical to the calculation of primary disability benefits.

A secondary condition is one that develops as a result of a service-connected disability. Common examples include:

  • Sciatica caused by a service-connected back injury
  • Depression that results from chronic pain
  • Migraines that stem from PTSD
  • Sleep disorders secondary to mental health conditions

Once the VA grants service connection for a secondary condition, it assigns a percentage, just like any other. You include its rating in the VA math just as you would for a primary condition, using the efficiency method or the combined ratings table.

Do Secondary Conditions Impact the Combined Rating Equally?

Yes. Secondary conditions are treated identically to primary ones in VA math. They’re not discounted or weighted differently. Once approved, they fully contribute to your overall disability percentage. This means that if you develop a new issue tied to an existing condition, it can increase your total rating and potentially raise your monthly compensation.

Common VA Math Mistakes to Watch For

Even the VA can make errors when calculating combined ratings. Here are some of the most common issues to watch for when you review your rating decision:

  • Ratings added together directly instead of using the efficiency method
  • Ratings not ordered from highest to lowest
  • The bilateral factor omitted when paired conditions are present
  • Confusion of combined rating with monthly payment percentage (payments refer to the VA pay chart)
  • Secondary conditions miscalculated as different from primary ones

How VA Math Affects Your Monthly Compensation

Your combined disability rating directly determines your monthly VA compensation and benefit eligibility. It reflects your overall loss of earning capacity, not just the number of conditions you have.

For example, in 2023:

  • A 70% rating = $1,564.71 per month
  • An 80% rating = $1,944.15 per month

That 10% difference is worth nearly $4,500 more per year. Higher ratings can unlock more than just money. Here’s what else you may get access to with a higher rating:

  • VA healthcare eligibility with expanded services
  • Caregiver support programs for family members
  • Specially Adapted Housing and vehicle modification grants
  • Vocational Rehabilitation and Employment Services
  • Dental care and other specialized treatments

VA Math, Explained

The VA calculates your disability rating for you, but that doesn’t mean you should accept it without question. Take the time to verify your combined rating using both the step-by-step method and the official VA math chart. Keep detailed records of all your conditions and their individual ratings. Don’t overlook secondary conditions, either. They can boost your combined rating.

Consider working with a veterans service organization or accredited representative if you believe your combined rating is incorrect. The VA’s math system might seem complicated, but it’s designed to fairly represent your overall disability level. Once you understand how it works, you can better advocate for yourself (or loved ones) and make informed decisions about your benefits.

References

U.S. Code of Federal Regulations. “§ 4.25 Combined ratings table.” Title 38—Pensions, Bonuses, and Veterans’ Relief; Chapter I—Department of Veterans Affairs; Part 4—Schedule for Rating Disabilities; Subpart A—General Policy in Rating. Electronic Code of Federal Regulations via Legal Information Institute, Cornell Law School. Available at: https://www.law.cornell.edu/cfr/text/38/4.25 Cornell Law School

Hersey, Linda F. “VA’s disability calculator produced wrong results, costing some vets thousands of dollars.” Stars and Stripes, 6 June 2025. Available at: https://www.stripes.com/veterans/2025-06-06/veterans-disability-payments-calculator-18032340.html stripes.com