Why 50% and 30% make 70%, not 80%
VA does not add ratings. It treats you as a whole person and applies each rating, largest first, to what is left. A 50% rating leaves 50% "efficiency". A 30% rating then takes 30% of that 50, which is 15. Together they make 65, and VA rounds to the nearest 10, so the result is 70%. This method comes from the combined ratings table in 38 CFR 4.25.
The bilateral factor
When you have ratings on both arms, both legs, or paired skeletal muscles, VA first combines those ratings together, then adds 10% of that combined value before combining it with your other ratings (38 CFR 4.26). For example, 10% on each knee combines to 19, plus 1.9 for the bilateral factor, giving 20.9, which then goes into the main calculation. Tick "Arm or leg" on each rating that belongs to that pair.
When dependents count
Dependents raise the payment only at a combined rating of 30% or higher. A spouse, each child under 18, each child aged 18 to 23 in school, and up to two dependent parents each add a set amount. If your spouse needs help with daily activities, Aid and Attendance adds more. Ratings of 10% and 20% are paid at one flat rate.
What this calculator does not cover
Special monthly compensation (SMC) for loss of use or the need for daily help, individual unemployability (TDIU), and temporary 100% ratings follow separate rules and are not included. Your decision letter shows how VA rated you.