TowingMath

Payload Capacity Calculator

Payload is what usually runs out first, not tow rating. Enter your placard payload and what you are carrying to see what is actually left.

Your numbers

From the yellow door-jamb placard: "occupants and cargo should never exceed".
Roughly 13% of loaded trailer weight if unmeasured.
A weight distribution hitch is typically 70-100 lb.
Payload remaining —

Enter your numbers above.

Verify before you tow. These figures are a planning aid, not professional or engineering advice. Your real limits are the ones printed on your vehicle's door-jamb placard, your trailer's VIN plate, and your owner's manual - and those override anything calculated here. When numbers are close, weigh the rig and go with the more conservative answer.

The formula

Payload capacity = GVWR - curb weight
                   (or read it straight off the door placard)

Payload remaining = Payload capacity
                  - passengers
                  - cargo and accessories
                  - trailer tongue weight
                  - hitch hardware

Worked example

A half-ton crew cab with 1,600 lb on the placard, towing a 6,000 lb travel trailer at 13% tongue weight, with two adults and a child, camping gear in the bed, and a weight distribution hitch: 

Payload capacity                        1,600 lb
Passengers (2 adults + 1 child)          -450 lb
Cargo in bed                             -200 lb
Tongue weight (6,000 x 0.13 = 780)       -780 lb
Weight distribution hitch                 -90 lb
                                        ---------
Payload remaining                          80 lb

80 lb left. This rig is legal but has essentially no margin - a full cooler and a case of water puts it over GVWR. And note that the trailer here is only 6,000 lb, far below the tow rating this truck advertises. The tow rating was never the limit.

This is why the tow rating on a brochure is close to meaningless on its own. Check what you can actually tow using GCWR, and read how the four ratings interact.

Common questions

What is payload capacity?

Payload is everything you add to the tow vehicle: passengers, pets, fuel beyond what the curb weight assumed, tools, gear in the bed, aftermarket accessories, the hitch hardware itself, and the trailer's tongue weight.

It is GVWR minus curb weight. Your door-jamb placard states it directly as "the combined weight of occupants and cargo should never exceed X lb", and that placard figure is the one to trust - it accounts for the options actually fitted to your specific truck.

Does tongue weight count against payload?

Yes, entirely, and this is the detail that overloads more trucks than anything else. A conventional trailer puts 10-15% of its loaded weight straight down onto the hitch, and every pound of that is payload.

A 9,000 lb travel trailer at 13% puts 1,170 lb on the tongue. On a half-ton truck with 1,500 lb of payload, that leaves 330 lb for the driver, passengers and everything in the cab - which is not enough for a family. The truck is over its GVWR long before it is anywhere near its tow rating.

Why is my payload lower than the brochure says?

Brochure payload figures describe the lightest configuration of a model line - regular cab, two-wheel drive, base engine, no options. Every option you added subtracts from it: four-wheel drive, a crew cab, a sunroof, a bigger engine, running boards.

The yellow placard on your driver's door jamb is specific to your VIN. Use it, not the brochure.

What happens if I exceed payload?

You are over GVWR, which means braking distances lengthen, suspension and tires operate outside their design range, and handling degrades - all at once, and typically when the rig is loaded for a trip.

It also has consequences beyond physics. Being over a manufacturer rating can affect insurance claims and, for a commercial operator, roadside enforcement.

Related tools

Sources