Consumer Reports discusses Payload designations such as half-ton, 3/4-ton, and 1-ton saying that they have little meaning except that a pickup truck is usually named according to its payload. There are some newer half-ton trucks that actually have payload ratings close to 1,000 lbs. However, most of these trucks are actually rated to carry 1500 lbs. give or take a few. However, the 3/4- and 1-ton pickups can carry much more weight than their rating would indicate. For example a 3/4-ton GMC has a GVWR (Gross Vehicle Weight Rating) of 8600 lbs., when subtracting the wet curb weight off 5300 libs it leaves a payload capacity of 3300 lbs. The brakes will have more impact on determining payload rating on some models. Most dual rear wheel 1-tons have a maximum payload of up to 5,000 lbs.because of the extra tires and better brakes.
Every dealer publishes a payload guide that will help determine the payload capacity depending on the payload. Beyond this, the condition of the vehicle powertrain, brakes and tires will be payload determinants.