Tongue Weight Percentage Calculator: The Method, a Worked Example and the Limits

Tongue Weight Percentage 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.

tongue weight percentage calculator: The method: the lowest of three ratings

Start with three numbers and keep the smallest: the vehicle tow rating, the tow-bar rating and the trailer ATM (aggregate trailer mass, the maximum loaded weight the trailer is rated for). The worked example on this page uses a vehicle rating of 6,500 lbs, a tow-bar rating of 7,500 lbs and a trailer ATM of 6,500 lbs, so the capacity is 6,500 lbs — whichever of the three is lowest. Treat those as example figures: your own numbers come from the owner's manual, the tow-bar plate and the trailer plate. The rule is strict because each rating protects something different — the vehicle's drivetrain, brakes and cooling; the tow bar and its fixings; the trailer's running gear — and the combination is only as strong as its weakest part.

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 percentage calculator: Where to find your ratings

Four plates and documents carry the whole answer. The owner's manual lists tow ratings by engine, axle ratio and configuration and states GVWR and GCWR. The driver's door-jamb sticker gives the GVWR and payload for your exact vehicle as built. The tow-bar rating plate sits on the bar or by the receiver. The trailer's compliance plate shows its ATM and tare weight. Read all four, and if two sources disagree, use the lower figure and ask a dealer to confirm for your VIN. Ratings shift with engine, axle ratio, cab, bed length and tow package, so a figure for a different configuration — or one copied from a forum — is not a substitute.

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

For tongue weight percentage calculator, the point is this: 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.

tongue weight percentage calculator: How to measure tongue weight

On this page, tongue weight percentage calculator is the case in point: 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 percentage calculator

Take a 5,000 lbs loaded trailer as the example. The vehicle's tow rating is 6,500 lbs, the tow-bar rating is 7,500 lbs and the trailer ATM is 6,500 lbs. The towing capacity is the lowest of the three: 6,500 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 percentage calculator

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 tongue weight percentage calculator.

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 tongue weight percentage calculator

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 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

tongue weight percentage calculator: Common mistakes

  • On this page, tongue weight percentage calculator is the case in point: Using the trailer's empty weight instead of its loaded weight. A trailer's tare weight is the empty figure; the loaded weight is what the ratings are tested against, and water, gas, luggage and equipment can add hundreds of pounds.
  • Taking tongue weight percentage 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 percentage 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 percentage calculator, the point is this: Taking the highest rating and ignoring the other two. The vehicle rating, the tow-bar rating and the trailer ATM are all limits, and the lowest one decides — a strong vehicle with a light tow bar is limited by the tow bar.

tongue weight percentage calculator: Related calculations

On this page, tongue weight percentage calculator is the case in point: These pages continue from here: the same method on a neighbouring question, or the calculator that runs the arithmetic for you.

tongue weight percentage calculator: Putting your figure to work

For tongue weight percentage calculator, the point is this: 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

What is noseweight for a caravan?

Taking tongue weight percentage calculator as the case in point: 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.

Can I exceed my towing capacity?

Taking tongue weight percentage calculator as the case in point: 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.

Do I need a special licence to tow?

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

Do I need trailer brakes?

On this page, tongue weight percentage calculator is the case in point: That depends on the trailer's weight and local rules: heavier trailers generally require their own brakes, and the threshold varies by country and by state. Check the trailer's ATM, the tow vehicle's manual and the local regulations. A trailer with brakes stops shorter and puts less load on the tow vehicle's brakes, which is why the braking requirement exists.

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 6,500 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.