The amount of your monthly Social Security disability benefits is completely based on your lifetime average earnings reported to Social Security and the taxes you paid into the system.
Each year you should receive a green pamphlet from the Social Security Administration around the time of your birthday. This form does not just give you an estimate of your estimated retirement benefits. It also lets you know whether you have enough credits to qualify for disability, and provides you an estimate of your monthly disability benefits. Look at the top of page two for these estimates.
If you do not already have an estimate or have misplaced your form, you can use Social Security’s Benefit Calculators to determine how much you would received in disability benefits if you became disabled right now.
Also check out the following link to learn about out how other payments you receive may affect your disability benefits.