Subtract the curb weight from the GVWR to find the payload capacity. For example, if you have a light-duty truck with a GVWR of 9,000 pounds and a curb weight of 6,000 pounds, the payload capacity will be 3,000 pounds: GVWR – curb weight = payload capacity. 9,000 pounds – 6,000 pounds = 3,000 pounds.