Tongue Weight Calculator: What to Check Before You Tow Anything

Tongue Weight Calculator is the part of towing maths most people skip, and the part that causes the most trouble when it is wrong. Tongue weight is the downward force the trailer puts on the tow hitch, and the working rule is 10 to 15 percent of the trailer's loaded weight. Too little and the trailer sways; too much and the tow vehicle's steering goes light and its rear suspension bottoms out. This page shows the formula, works through examples at several trailer weights, and explains how to measure it with a scale.

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 tongue weight calculator

Towing capacity is the lowest of three numbers: the vehicle's tow rating, the tow-bar rating and the trailer's ATM (aggregate trailer mass — the maximum the trailer itself is rated to weigh when loaded). If any one of them is lower than the others, that one is the limit. In this page's worked example the three ratings are 11,000 lbs for the vehicle, 5,000 lbs for the tow bar and 4,500 lbs for the trailer ATM, so the towing capacity is 4,500 lbs — the lowest of the three. Those are example figures, not ratings for any particular vehicle: substitute the three numbers from your own owner's manual, tow-bar plate and trailer plate and the same step gives your answer. The reason the rule exists is that each rating protects a different part of the combination — the vehicle's engine, transmission, brakes and cooling; the tow bar and its mounting; and the trailer's axles, tyres and brakes — and the weakest of the three decides what is safe to pull.

That is only the first check. The second check is the weight the vehicle itself carries: GVWR is the maximum the loaded vehicle may weigh, GCWR is the maximum the vehicle and trailer together may weigh, and payload is the difference between the vehicle's kerb weight and its GVWR. Tongue weight counts against payload, so a heavy trailer reduces the passengers and cargo you can carry. If the combination is inside the tow rating but over GCWR or over payload, it is still overloaded. All three limits have to be satisfied at the same time, and the owner's manual and door-jamb sticker are where the numbers for your exact vehicle live.

tongue weight calculator: Where to find your ratings

The owner's manual is the first source: it gives the tow rating for each engine, axle ratio and configuration, plus the GVWR and GCWR. The door-jamb sticker on the driver's door is the second — it shows the GVWR and payload for your vehicle as built, which is the figure that counts, because factory-fitted options change it. The tow bar carries its own rating plate near the receiver, and the trailer's compliance plate shows its ATM and its tare weight. Where the manual and the sticker disagree, take the lower number and have a dealer confirm it against your VIN. A rating quoted for a different year, engine or trim is not your rating, and neither is a number from a forum or a sales listing.

Tongue weight: the 10 to 15 percent rule for tongue weight calculator

On this page, tongue weight calculator is the case in point: Tongue weight should be 10 to 15 percent of the trailer's loaded weight. For a 5,000 lbs trailer that is 500 to 750 lbs, with about 625 lbs as a good middle target. Below 10 percent the trailer is prone to sway, because there is not enough downward force on the hitch to keep it tracking straight; above 15 percent the tow vehicle's rear suspension is overloaded, the steering goes light and the headlights point at the sky. The fix for wrong tongue weight is loading, not guessing: move heavy items forward of the trailer axle to increase it, or behind the axle to reduce it, and re-weigh. Never fix sway by adding speed — slow down, and check the loading before the next trip.

How to measure tongue weight for tongue weight calculator

For tongue weight calculator, the point is this: The accurate way is a tongue-weight scale under the coupler with the trailer level and loaded as it will travel. A bathroom scale and a lever can work for lighter trailers, but the reading is only as good as the setup, so a proper scale is worth it for anything heavy. Measure with the trailer loaded as it will travel — water tanks, gas bottles, luggage and all — because an empty trailer tells you nothing about the loaded figure. Record the number, divide it by the trailer's loaded weight, and check the percentage is inside 10 to 15 percent. If it is not, reload and measure again.

Worked example: the three ratings and the payload check for tongue weight calculator

Take a 5,000 lbs loaded trailer as the example. The vehicle's tow rating is 11,000 lbs, the tow-bar rating is 5,000 lbs and the trailer ATM is 4,500 lbs. The towing capacity is the lowest of the three: 4,500 lbs. The trailer's tongue weight at 10 to 15 percent is 500 to 750 lbs, and the middle of that range — about 625 lbs — is a good target. With an example payload of 2,000 lbs, the tongue weight leaves 1,375 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.

Tongue weight table for tongue weight calculator

Taking tongue weight calculator as the case in point: Use the table to read off the tongue-weight range for your loaded trailer weight. The middle column, 12.5 percent, is a handy loading target. Every figure is worked out from the trailer weight, so weigh the loaded trailer rather than guessing it.

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

tongue weight calculator: The four checks, in order

Check What to compare Passes when
Tow rating Trailer weight vs lowest of vehicle, tow-bar and trailer ATM ratings Trailer weight is at or below the lowest rating
Tongue weight Tongue weight against 10–15% of trailer weight Percentage sits inside 10–15%
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

Common mistakes for tongue weight calculator

  • 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. That is the point this page works through for tongue weight calculator.
  • Taking tongue weight calculator as the case in point: 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 tongue weight calculator as the case in point: Hitching up without checking the coupler is locked. A coupler that looks seated but is not latched can come off on the first bump, and the safety chains are a last resort, not a towing method.
  • For tongue weight calculator, the point is this: 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.

tongue weight calculator: Related calculations

If this page answered your question, these pages take the next step — the same method applied to a closely related question, or the calculator that does the arithmetic for you. That is the point this page works through for tongue weight calculator.

Putting your figure to work for tongue weight calculator

The check only helps if you run it on your own numbers every time the load changes. Weigh the trailer as it will travel, take the three ratings from your manual and plates, work out the tongue weight and check payload and GCWR. Keep the four answers with the trailer's paperwork — lowest rating, tongue-weight range, payload left over, GCWR headroom — and redo them when anything changes: a full tank, another passenger, a different trailer. Loads change, so the answer changes, and the habit of re-checking is what keeps the combination legal and stable. That is the point this page works through for tongue weight calculator.

Frequently asked questions

What is noseweight for a caravan?

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. That is the point this page works through for tongue weight calculator.

What is tongue weight and why does it matter?

For tongue weight calculator, 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 5,000 lbs trailer that is 500 to 750 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.

How do I work out my towing capacity?

Take the lowest of three ratings: your vehicle's tow rating, your tow-bar rating and the trailer's ATM. Then check the tongue weight is 10 to 15 percent of the trailer weight, and check the combination against GVWR, GCWR and payload. All four checks have to pass. The ratings come from your owner's manual, the door-jamb sticker, the tow-bar plate and the trailer plate — not from a figure quoted for a different vehicle.

Can I exceed my towing capacity?

For tongue weight calculator, the point is this: No. The tow rating is a maximum set by the manufacturer for the vehicle's engine, transmission, brakes and cooling, and exceeding it increases braking distances, overheats the transmission, reduces stability and can be illegal. It can also void warranty coverage and give an insurer a reason to refuse a claim. If the trailer is heavier than the lowest of the three ratings, you need a different vehicle, a different tow bar or a lighter load.

What is trailer ATM?

On this page, tongue weight calculator is 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.