How to Calculate GCWR: Method First, Then the Numbers

How to Calculate GCWR is the number that caps the whole combination: tow vehicle plus trailer, fully loaded. GCWR is the maximum weight of the vehicle and the trailer together, and it is the limit that catches people who check the tow rating but forget the payload. This page explains what GCWR means, how it relates to GVWR, and how to work out whether your combination is inside it.

Never exceed your vehicle's GVWR, GCWR or payload. Check the owner's manual and the door-jamb sticker for the ratings that apply to your exact vehicle, and treat every figure on this page as a worked example unless it comes from your own vehicle's plates.

The method: the lowest of three ratings for how to calculate gcwr

Three ratings decide what you may tow, and the answer is the smallest of them: the vehicle's tow rating, the tow-bar rating and the trailer's ATM — the aggregate trailer mass, the most the loaded trailer is rated to weigh. Here the worked example uses 5,000 lbs for the vehicle, 4,000 lbs for the tow bar and 6,500 lbs for the trailer ATM, which makes the towing capacity 4,000 lbs. Those numbers are examples, not ratings for any real vehicle: read the three figures off your own manual and plates and the same step gives your answer. Each rating guards a different part of the rig — the vehicle's engine, transmission, brakes and cooling; the tow bar and its mounting; the trailer's axles, tyres and brakes — so the weakest link sets the limit.

The tow rating alone is not the whole answer. GVWR caps the loaded vehicle, GCWR caps the vehicle and trailer together, and payload — GVWR minus kerb weight — caps what the vehicle itself may carry, including the tongue weight pressing down on the hitch. A heavy trailer therefore eats into the passengers and cargo you can carry, and a combination can be inside the tow rating yet still overloaded on GCWR or payload. Every limit has to pass at once, and the numbers for your exact vehicle are in the owner's manual and on the door-jamb sticker.

Where to find your ratings for how to calculate gcwr

Start with the owner's manual: it lists the tow rating by engine, axle ratio and configuration, and it states the GVWR and GCWR. Then check the door-jamb sticker on the driver's door, which gives the GVWR and the payload for your exact vehicle as built — this is the number that matters, because options fitted at the factory change it. The tow bar itself has a rating plate, usually stamped on the bar or on a label near the receiver, and the trailer has a compliance plate showing its ATM and its tare (empty) weight. If the manual and the sticker disagree, use the lower figure and ask a dealer to confirm for your VIN. Never take a rating from a forum, a sales listing or a figure quoted for a different year or engine: ratings change with engine, axle ratio, cab, bed length and tow package, and the only numbers that count are the ones for your vehicle.

GVWR, GCWR and payload: how they fit together

GVWR is the maximum the loaded vehicle may weigh. GCWR is the maximum the vehicle and the trailer together may weigh. Payload is GVWR minus the vehicle's kerb weight — the weight of passengers, cargo, fuel and tongue weight the vehicle may carry. In this page's example the payload is 1,600 lbs. A trailer of 6,000 lbs puts about 750 lbs of tongue weight on the hitch, which leaves 850 lbs of payload for everything else. That is the check people miss: a vehicle can be inside its tow rating and still overloaded, because the tongue weight plus the family plus the luggage exceeds the payload. Work the payload check every time you load up, not just when you buy the trailer.

how to calculate gcwr: Worked example: the three ratings and the payload check

Take a 6,000 lbs loaded trailer as the example. The vehicle's tow rating is 5,000 lbs, the tow-bar rating is 4,000 lbs and the trailer ATM is 6,500 lbs. The towing capacity is the lowest of the three: 4,000 lbs. The trailer's tongue weight at 10 to 15 percent is 600 to 900 lbs, and the middle of that range — about 750 lbs — is a good target. With an example payload of 1,600 lbs, the tongue weight leaves 850 lbs for passengers and cargo. If the passengers and luggage weigh more than that, the combination is overloaded even though the trailer is inside the tow rating, and something has to come off — either the trailer load or the vehicle load. That is the whole check in one paragraph: lowest of three, then tongue weight, then payload, then GCWR. Do it with your own numbers before every trip, because the answer changes every time the load changes.

how to calculate gcwr: Tongue weight table

The table shows the 10 to 15 percent tongue-weight range for common loaded trailer weights. The middle column is 12.5 percent, a useful target when you are loading. All figures are calculated from the trailer weight — weigh your own trailer, do not guess it. That is the point this page works through for how to calculate gcwr.

Loaded trailer weight (lbs) 10% tongue weight 12.5% tongue weight 15% tongue weight
3,500 350 438 525
5,000 500 625 750
6,000 600 750 900
7,000 700 875 1,050
10,000 1,000 1,250 1,500

The four checks, in order for how to calculate gcwr

Check What to compare Passes when
Tow rating Trailer weight against the lowest of the three ratings Trailer is at or below the lowest rating
Tongue weight Tongue weight vs 10–15% of trailer weight Inside the range
Payload Tongue weight plus passengers and cargo against payload Sum is at or below payload
GCWR Vehicle + trailer loaded weights vs GCWR Combined weight is at or below GCWR

how to calculate gcwr: Common mistakes

  • Taking how to calculate gcwr as the case in point: Loading the trailer tail-heavy to reduce tongue weight. Putting weight behind the axle lightens the hitch, but it is the fastest way to make a trailer sway, and sway at speed is far more dangerous than a heavy hitch.
  • For how to calculate gcwr, the point is this: Driving at solo speeds while towing. Speed limits for towing are lower in most places, and stopping distances and sway risk both grow sharply with speed, so the right speed while towing is well below the solo limit.
  • Taking how to calculate gcwr as the case in point: Ignoring the GCWR. A combination can be inside the tow rating and still over the GCWR once the vehicle is fully loaded with people and luggage.
  • Taking how to calculate gcwr as the case in point: Guessing the trailer's weight instead of weighing it. Bathroom scales and guesswork are not a substitute for a weighbridge or a proper scale, and an overloaded trailer is the most common cause of towing trouble.

Related calculations for how to calculate gcwr

On this page, how to calculate gcwr is the case in point: For the next step, these pages apply the same method to a closely related question — or hand the arithmetic to the calculator.

how to calculate gcwr: Putting your figure to work

On this page, how to calculate gcwr is the case in point: Putting the figure to work means doing the check with your own numbers before every trip, not once when you buy the trailer. Weigh the loaded trailer, read the three ratings off your own manual and plates, work out the tongue weight, and check the payload and GCWR. Write the four numbers down and keep them with the trailer's documents: the lowest of the three ratings, the tongue-weight range, the remaining payload and the GCWR headroom. When the load changes — a full water tank, an extra passenger, a different trailer — redo the check, because the answer changes with the load. That habit is what keeps a towing combination inside its limits on the road, not just on paper.

Frequently asked questions

Do I need a special licence to tow?

For how to calculate gcwr, the point is this: It depends on where you are and how heavy the combination is. Licence categories limit the combined weight you may tow, and the rules differ by country. Check your licence entitlement before towing, not after you are stopped.

What is tongue weight and why does it matter?

For how to calculate gcwr, the point is this: Tongue weight is the downward force the trailer puts on the hitch. It should be 10 to 15 percent of the trailer's loaded weight — for a 6,000 lbs trailer that is 600 to 900 lbs. Too little causes sway; too much overloads the tow vehicle's rear suspension and lightens the steering. Load the trailer to get the percentage right, then re-weigh.

What is noseweight for a caravan?

For how to calculate gcwr, the point is this: Noseweight is the UK term for the downward force a caravan puts on the tow ball — the same thing as tongue weight. The commonly quoted guideline for caravans is 5 to 7 percent of the caravan's loaded weight, lower than the 10 to 15 percent used for other trailers, because caravans are designed around it.

How much trailer can I tow?

It depends on the lowest of your vehicle's tow rating, your tow-bar rating and the trailer's ATM, capped by GVWR, GCWR and payload. In this page's worked example the lowest rating is 4,000 lbs. Substitute your own three ratings and run the same check — the answer is specific to your vehicle and your trailer, not a general figure.

What is trailer ATM?

Taking how to calculate gcwr as the case in point: ATM is the aggregate trailer mass: the maximum the trailer is allowed to weigh when fully loaded, set by the trailer manufacturer. It is on the trailer's compliance plate, and it is one of the three ratings in the lowest-of-three rule — your towing capacity can never exceed the trailer's ATM.