If you have more than one service-connected condition, you’ve probably done the math yourself: add up your percentages and assume that’s your rating. A 30% rating plus a 20% rating should equal 50%, right?

It doesn’t. The VA doesn’t add disability ratings together. Instead, it uses what’s called the combined ratings formula, described in 38 CFR §4.25, which almost always produces a lower number than simple addition would. Understanding this formula — and how the bilateral factor changes it — is the difference between guessing at your rating and knowing it.

Use the calculator on this page to get your estimated combined rating instantly, or read on to understand exactly how the VA arrives at that number.

How the VA Combined Ratings Formula Works

The VA treats you as a “whole person” starting at 100% efficiency. Each disability doesn’t subtract a flat percentage from 100 — it takes a percentage of what’s left.

Here’s the process:

1. List all your individual disability ratings and sort them from highest to lowest.
2. Start with your highest rating. That becomes your “efficient” percentage remaining is 100% minus that rating.
3. For your next-highest rating, apply that percentage to the remaining efficiency — not to the original 100%.
4. Add that result to your running total, and repeat for every remaining condition.
5. Round the final number to the nearest 10%.

Example: Say you have a 50% rating and a 30% rating.

• Start with 50%. Remaining efficiency: 100% − 50% = 50%.
• Apply 30% to that remaining 50%: 30% × 50% = 15%.
• Running total: 50% + 15% = 65%.
• Rounded to the nearest 10%: 70%.

Notice this isn’t 50 + 30 = 80%. The VA’s method almost always gives you a lower combined number than adding ratings directly, which is why veterans are often surprised by their official rating letter.

What Is the Bilateral Factor?

If two or more of your conditions affect paired body parts — both knees, both shoulders, both arms — the VA applies an extra 10% bonus called the bilateral factor (38 CFR §4.26).

Here’s how it’s calculated:

1. Combine the paired-limb ratings together first, using the same formula above.
2. Add 10% of that combined value as a bonus.
3. Take that bonus-adjusted number and combine it with your other, non-paired ratings using the standard formula.

Example: A 20% rating for your left knee and a 20% rating for your right knee.

• Combine 20% and 20%: 20% + (80% × 20%) = 36%.
• Add the 10% bilateral bonus: 36% × 1.10 = 39.6%.
• That 39.6% then gets combined with any other ratings you have, and the final total is rounded to the nearest 10%.

You can have more than one bilateral group too — for example, a knees group and a separate shoulders group — each getting its own 10% bonus before everything is combined together at the end.

Why the Rounding Step Matters

After all your individual and bilateral calculations are combined, the VA rounds the final decimal number to the nearest 10. A combined value of 63% rounds down to 60%, while 65% or higher rounds up to 70%. This is also why the order you combine ratings in doesn’t change the final rounded result, even though it can look different mid-calculation.

Try the Calculator

Rather than working through the math by hand, enter your individual ratings into the calculator on this page. It applies the same combined-ratings formula and bilateral factor the VA uses, and shows you the full step-by-step breakdown so you can see exactly how your final percentage was reached.

This tool is for informational purposes only and is not affiliated with the Department of Veterans Affairs. It doesn’t account for special protections like unemployability (TDIU) or pyramiding rules. Always confirm your official rating with the VA or an accredited Veterans Service Officer (VSO).

Frequently Asked Questions

Does the VA just add up my disability percentages?
No. The VA uses a combined ratings formula where each additional rating is applied to your remaining “efficiency,” not simply added to your other ratings. This typically results in a lower total than straight addition.

What is the bilateral factor?
It’s a 10% bonus applied when two or more of your ratings affect paired body parts, like both legs or both arms. The paired ratings are combined together first, then the bonus is added, before combining with your other conditions.

How does the VA round my final combined rating?
The final combined percentage is always rounded to the nearest multiple of 10. For example, 63% rounds down to 60%, and 65% rounds up to 70%.

Can I have more than one bilateral group?
Yes. If you have paired ratings in different body regions — say, both knees and separately both shoulders — each pair can be treated as its own bilateral group, each receiving its own 10% bonus, before all values are combined into your final rating.

Is this calculator official or affiliated with the VA?
No. This tool is independently built to replicate the VA’s published combined ratings formula for estimation purposes. Your official rating is determined by the VA based on your full claims file.

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