Read this before the arithmetic
The ratings in this calculator have to come off your own vehicle. GVWR and the axle ratings are on the certification label in the driver's door jamb; GCWR and the tow rating for your exact drivetrain, axle ratio and hitch are in the owner's manual or the towing supplement for that model year. This page does nothing but arithmetic on the figures you type into it. It is not a tow rating, not an approval, and not a substitute for weighing the rig on a scale. Towing rules — licence class, trailer brakes, breakaway systems, mirrors, chains, speed limits and what you may legally tow at all — vary by state, province and country, and none of them are modelled here.
What this page can do is the subtraction, which is where most people go wrong — not because the arithmetic is hard, but because the tongue weight gets left out of the payload column, or the vehicle is weighed empty and then loaded with four adults and a toolbox, or the trailer's dry weight from the brochure is used instead of what it weighs full of gear, water and fuel. Those three mistakes account for the great majority of overloaded rigs on the road.
The four ratings and what each one governs
| Rating | What it limits | Where you find it |
|---|---|---|
| GVWR | The loaded vehicle on its own wheels, including tongue weight | Certification label, driver's door jamb |
| GAWR front / rear | Each axle separately. Both must be satisfied, not just the total. | Same label |
| GCWR | Vehicle and trailer together | Owner's manual or towing supplement, rarely on the label |
| Payload | GVWR minus the vehicle's actual empty weight | Often a separate yellow sticker; otherwise you subtract |
Two of these catch people out. GAWR is per axle, and a rig can be comfortably inside GVWR while the rear axle is over its own rating, which is exactly what heavy tongue weight does. And the payload figure on the sticker is specific to that vehicle as it left the factory — every accessory bolted on since comes out of it.
Where the tongue weight goes
This is the single most misunderstood part of the calculation, so it is worth being explicit. Tongue weight is not an extra load added to the trailer. It is the portion of the trailer's weight that rests on the hitch ball instead of on the trailer's own wheels. That means it counts twice in two different sums, and once in a third:
- Against GVWR: tongue weight is payload. It sits on the vehicle's wheels, so it comes out of the same pot as passengers and cargo.
- Against GAWR: it lands mostly on the rear axle, and a weight-distributing hitch moves some of it forward but does not make it disappear.
- Against GCWR: it is counted once, inside the trailer weight. Adding it again on top would double-count it, and this calculator does not.
A 6,000 lb trailer at 12 percent puts 720 lb on the hitch. On a truck with 1,600 lb of payload, nearly half the capacity is gone before anybody gets in. Ten to fifteen percent is the range commonly quoted for a conventional ball hitch, with fifth-wheel and gooseneck arrangements running higher and taking a far larger share out of payload. Where a specific trailer should sit is the trailer manufacturer's figure, and the only way to know what yours is doing is to weigh it.
Which limit runs out first
The tool shows the largest trailer each rating permits with everything else held constant. On modern half-ton trucks it is almost always payload rather than GCWR that binds, and that is the opposite of what the advertising leads people to expect. A truck advertised as towing 11,000 lb typically reaches that figure only in a specific configuration, with the lightest cab and bed, no options, one 150 lb occupant and nothing in the bed. Add a crew cab, four-wheel drive, a sunroof, a family and a weight-distributing hitch, and several hundred pounds of payload have gone before the trailer is connected.
This is why "can my truck tow it" is the wrong question and "what is left after the tongue" is the right one.
Weigh it
Every figure above is only as good as the weights you put in, and two of them are routinely wrong. Brochure curb weights describe a base configuration nobody buys, and trailer dry weights exclude the battery, the propane, the fresh water, the gear and everything else that makes a trailer useful. A public scale will give you the truth for a few dollars: weigh the loaded vehicle alone, then the whole rig together, then the vehicle with the trailer still coupled but its wheels off the platform, and the differences give you actual axle loads and actual tongue weight. Do that once with a typical load and you will know whether the arithmetic on this page describes your rig or merely flatters it. If any of it comes out close to a rating, close is not good enough — get the real numbers, and get advice from someone who can look at the vehicle, the hitch and the trailer together.
Questions people ask
Where do I find my vehicle's GVWR and payload?
GVWR is printed on the certification label, a sticker in the driver's door jamb or on the B-pillar, along with the front and rear GAWR figures and the original tire and pressure specification. Many vehicles carry a second sticker, often yellow, giving a combined weight of occupants and cargo that should never be exceeded — that is your payload as the vehicle left the factory, and it is specific to that vehicle rather than to the model. GCWR is usually not on either label; it lives in the owner's manual or in the towing supplement, broken out by engine, axle ratio, cab configuration and hitch type. If the vehicle has had accessories fitted since it was built, its real empty weight is higher than the factory figure and the payload sticker is optimistic by that amount. A trip to a public scale settles it. Do not take these figures from a forum, a sales listing or a specification site; get them off the vehicle in front of you.
Does tongue weight count against payload?
Yes, in full, and this is the mistake that puts most overloaded rigs on the road. The tongue weight is the part of the trailer's weight carried by the hitch ball rather than by the trailer's own wheels, so it is sitting on your vehicle's suspension exactly like cargo in the bed. It comes out of the same payload allowance as passengers and luggage. At a typical 10 to 15 percent of trailer weight, a 7,000 lb trailer puts 700 to 1,050 lb on the hitch, which is most of the payload on many half-ton pickups and all of it on many SUVs. A weight-distributing hitch redistributes that load between the axles and restores steering feel and headlight aim, but it does not reduce the total weight the vehicle is carrying, and the hitch hardware itself adds its own weight to the calculation.
What is the difference between GVWR and GCWR?
GVWR is the maximum weight of the loaded vehicle standing on its own four wheels — curb weight plus everybody in it, everything in it, and the tongue weight of anything hitched behind it. GCWR is the maximum for the vehicle and trailer together, and it exists because the engine, transmission, cooling system and brakes have a limit on the total mass they can accelerate, haul up a grade and stop, independent of how that mass is distributed. Both apply at once, along with the per-axle GAWR figures, and satisfying one says nothing about the others. Subtracting a loaded vehicle's weight from GCWR gives you the heaviest trailer that rating permits, but it is not a tow rating — the manufacturer publishes those separately for each configuration, and they are frequently lower than the GCWR subtraction suggests.
What happens if I exceed a rating?
Two categories of consequence, and the first is the one that matters. Mechanically, the ratings are what the brakes, tires, wheel bearings, springs, axles and frame were engineered and certified to handle with a margin. Over them, stopping distances lengthen, tires run hotter than their load rating allows, handling degrades in exactly the situations where you need it, and components fail progressively rather than all at once. Second, there are consequences on paper: an insurer assessing a claim, a manufacturer assessing a warranty repair and an investigator assessing a collision can all establish that a vehicle was loaded beyond its ratings, and the outcome of that is not something to find out about after the fact. Enforcement, licensing requirements and trailer brake rules also vary by jurisdiction and are outside what this page covers. If the numbers come out close to a limit, the answer is to move weight or change vehicles, not to round in your favour.