Weights and capacities
Tongue weight calculator
Tongue weight is the downward force the coupler puts on the ball. It is the single number that decides whether a trailer tracks straight or starts to sway, and almost nobody knows theirs, because a brochure figure is not a measurement.
Enter your weighed loaded trailer weight and your measured tongue weight. If you only have one of them, enter the trailer weight and read the target band instead.
Run your own numbers
Inside the 10 to 15 percent band. That is a starting point, not a clearance.
| Figure | Value |
|---|---|
| Tongue weight percentage | 12.0% |
| Target band at 10 to 15 percent | 700 to 1,050 lb |
| Sensible target at 12 to 13 percent | 840 to 910 lb |
| Spring bars this points at | 1,000 lb bars |
| Total out of tow vehicle payload | 940 lb |
Shown with the example figures above. Change any field to run your own numbers.
The working
Rule of thumbpercentage = tongue weight / loaded trailer weight x 100 target band = loaded trailer weight x 0.10 to x 0.15 payload used = tongue weight + hitch hardware
The 10 to 15 percent band is towing convention rather than a published standard. Widely taught towing convention rather than a published specification. It is a good starting point and it is not a rating.
Measure it, then carry it
A tongue weight scale turns the most important figure on the rig from a guess into a measurement. The weight distribution hardware below is ranked by published tongue weight rating against the figure you entered.
Equal-i-zer 4-point Sway Control Hitch, 16,000 lb
$745.35 Published ratingsThe top of the Equal-i-zer range at 16,000 lb and 1,600 lb of tongue weight. Worth checking your receiver rating before buying it, because very few receivers carry a weight distributing rating this high.
Best for: The heaviest bumper pull trailers, behind a truck with a Class V receiver.
Check price on Amazon
Equal-i-zer 4-point Sway Control Hitch, 14,000 lb
$688.83 Published ratingsThe same four point design rated for a 14,000 lb trailer and 1,400 lb of tongue weight, which is the band most large travel trailers land in once they are loaded with water.
Best for: A large travel trailer behind a three quarter ton truck.
Check price on Amazon Equal-i-zer 4-point Sway Control Hitch, 6,000 lb
$624.46 Published ratingsThe light end of the range, at 6,000 lb and 600 lb of tongue weight. Spring bars that are far too stiff for the tongue weight ride harshly and distribute badly, so sizing down to this one on a small trailer is the correct move rather than a compromise.
Best for: A smaller travel trailer where the 1,000 lb bars would be badly oversized.
Check price on Amazon Equal-i-zer 4-point Sway Control Hitch, 10,000 lb
$552.69 Published ratingsFour points of friction sway control built into the hitch itself rather than bolted on beside it, so there is no separate sway bar to disconnect before a tight turn or a wet ramp. The sway control works in both directions from the moment the bars are seated.
Check before buying: The four point design is audible. A rhythmic creak on slow tight turns is normal for this hitch and not a fault, but people who have not been warned about it return them.
Best for: A single or tandem axle travel trailer up to 10,000 lb where you want one part doing both jobs.
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Sherline Hydraulic Tongue Weight Scale Combo with 2,000 lb and 5,000 lb Gauges
$229.95Two gauges on one scale body, so a 400 lb tongue weight can be read on the 2,000 lb gauge where the resolution is useful rather than squinted at on the 5,000 lb one.
Best for: Somebody weighing both a light trailer and a heavy one.
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Sherline Hydraulic Tongue Weight Scale, 0 to 5,000 lb with dual scale gauge
$199.95Reads in both pounds and kilograms on one gauge, at 5,000 lb capacity.
Best for: Pin weight, with a metric reading for anybody who wants it.
Check price on AmazonEvery rating shown is the manufacturer's own published figure. The rating on the part you receive is what governs, and your own door jamb sticker governs everything above it.
On this page
Why too little tongue weight is the dangerous end
A trailer is a pendulum hinged at the ball. Load weight behind the trailer axle and the trailer centre of mass moves rearward, which lengthens that pendulum and reduces the tongue weight holding it steady at the same time. A gust, a passing truck or a steering correction then starts an oscillation the trailer has very little ability to damp, and it grows instead of dying out. That is trailer sway, and it is caused far more often by a tail-heavy load than by speed.
Too much tongue weight is a real problem too: it overloads the tow vehicle rear axle and lightens the steer axle. But it does not feed on itself. Err heavy, never light.
What the percentage means
A conventional trailer wants 10 to 15 percent of its loaded weight on the ball, and below 10 percent is the sway condition.
Rule of thumb Widely taught towing convention rather than a published specification. It is a good starting point and it is not a rating.
| Percentage | What it means | What to do |
|---|---|---|
| Under 9 percent | Well below the floor. This is the condition that produces sway. | Move cargo ahead of the trailer axle and re-weigh before driving. |
| 9 to 10 percent | Just under the floor, with no margin for a shifting load. | Move some weight forward. A rear tank filling on the road can drop you further. |
| 10 to 12 percent | Inside the band, at the light end. | Acceptable. Loading nearer 12 or 13 percent gives more margin. |
| 12 to 15 percent | The solid part of the band. | This is the target. Check it still fits your payload and hitch ratings. |
| Over 15 percent | Above the ceiling. Heavy on the rear axle, light on the steering. | Check the rear GAWR and the payload. A weight distribution hitch restores steering; it does not create capacity. |
The 10 to 15 percent band is taught by every trailer maker, every hitch maker and every towing school, and no standards body publishes it. It is a target, not a rating.
How to measure it rather than guess it
- Load the trailer the way you will tow it. Water in the tanks, propane on the A-frame, batteries connected, everything packed where it will ride. A tongue weight measured on an empty trailer tells you nothing useful.
- Get the trailer frame level. On level ground, with the coupler at the height that makes the FRAME level rather than wherever the jack happens to sit.
- Use a tongue weight scale, or a public scale. A scale under the coupler reads it directly. Or weigh the rig hitched at a public scale, unhitch, and weigh the tow vehicle alone on the same trip. The difference is your tongue weight, and you also get the real loaded trailer weight.
- Fix it by moving cargo, not by adjusting the hitch. Tongue weight comes from where the load sits relative to the trailer axle. No hitch adjustment changes where the trailer centre of mass is.
- Re-weigh after any real change. A second battery, a full fresh tank instead of an empty one, or a generator in the front box each move the number, and several of them move it a long way.
Which spring bars match a tongue weight?
Weight distribution spring bars are rated by TONGUE WEIGHT and should bracket the weighed figure, including everything bolted to the A-frame. Bars far too stiff ride harshly and distribute badly; bars too light bottom out and cannot do the job.
Spring bars are chosen by the weighed tongue weight, not by the trailer weight and not by a brochure figure.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Bar rating | Tongue weight range | Typical trailer weight |
|---|---|---|
| 400 lb bars | 200 to 400 lb | about 4,000 lb |
| 600 lb bars | 400 to 600 lb | about 6,000 lb |
| 800 lb bars | 600 to 800 lb | about 8,000 lb |
| 1,000 lb bars | 800 to 1,000 lb | about 10,000 lb |
| 1,200 lb bars | 1,000 to 1,200 lb | about 12,000 lb |
| 1,400 lb bars | 1,200 to 1,400 lb | about 14,000 lb |
| 1,700 lb bars | 1,400 to 1,700 lb | about 17,000 lb |
A weight distribution hitch does not raise any capacity. It moves load between axles and changes nothing about your payload, GVWR, GCWR or axle ratings.
Which hitch class carries it?
Hitch classes tell you what hardware fits. The rating on your own receiver governs and is frequently lower than the class ceiling.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Class | Receiver opening | Max trailer weight | Max tongue weight | With weight distribution |
|---|---|---|---|---|
| Class I | 1-1/4 in | 2,000 lb | 200 lb | none published |
| Class II | 1-1/4 in | 3,500 lb | 350 lb | none published |
| Class III | 2 in | 8,000 lb | 800 lb | 12,000 lb / 1,200 lb tongue |
| Class IV | 2 in | 10,000 lb | 1,000 lb | 14,000 lb / 1,400 lb tongue |
| Class V | 2-1/2 in | 17,000 lb | 1,700 lb | 20,000 lb / 2,000 lb tongue |
Frequently asked questions
What percentage should trailer tongue weight be?
Ten to fifteen percent of the loaded trailer weight on a conventional bumper pull trailer, and you should aim for the heavy half of that rather than the minimum. A fifth wheel is completely different at 15 to 25 percent pin weight, because the load sits over the truck rear axle rather than hanging behind it. Both bands are towing convention rather than published standards.
What happens if tongue weight is too low?
The trailer sways, and the sway grows rather than damping out. A trailer pivots at the ball like a pendulum, and a tail-heavy load moves its centre of mass rearward, lengthening that pendulum while reducing the weight holding it steady. A small yaw input then amplifies. This is why too little tongue weight is more dangerous than too much, even though both are wrong.
Does tongue weight count against my payload?
Yes, entirely. Tongue weight is carried by the tow vehicle, not the trailer, so it comes out of the payload figure on the yellow sticker in your driver door jamb along with passengers, gear and the hitch hardware itself. On most half ton trucks and nearly every SUV, payload runs out well before the tow rating does.
Can I use the brochure dry weight to work this out?
No, and it is the most common expensive mistake in towing. A brochure dry weight excludes dealer-installed options, batteries, propane and every drop of water, and water alone is 8.34 lb per gallon. Trailers routinely weigh over a thousand pounds more loaded than the brochure figure, and the tongue weight moves with it. Weigh the rig.
Do propane cylinders and batteries change tongue weight?
More than almost anything else, because they sit on the A-frame ahead of the trailer axle, which is the highest leverage position on the trailer. Two full 20 lb cylinders are about 74 lb including the steel bottles, and a group 24 battery is about 50 lb, so roughly 124 lb lands almost entirely on the tongue. Adding a second battery is a real tongue weight change.
Will a weight distribution hitch fix a low tongue weight?
No. A weight distribution hitch moves load between axles to restore steering, braking and headlight aim. It cannot change where the trailer centre of mass sits, which is what low tongue weight actually is. The fix for low tongue weight is moving cargo forward of the trailer axle and re-weighing, and no hitch substitutes for that.
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Researched, not professional advice. This page is compiled from published standards, manufacturer towing guides and product specifications, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are towing convention rather than published standards, and they are labelled that way wherever they appear. Nothing here overrides your own ratings. Work your payload sum before your tow rating, because payload is the limit that actually binds on most half ton trucks and nearly every SUV. Load a conventional trailer to 10 to 15 percent tongue weight and a fifth wheel to 15 to 25 percent pin weight, and never lighter: a tail heavy trailer is what starts sway. Weigh the rig loaded rather than trusting a brochure dry weight. A weight distribution hitch and a set of air bags both restore ride height and control, and neither one raises a single rating. Trailer brakes are required by state law above a threshold that varies by state, and a breakaway battery that has quietly gone flat is the normal condition of most trailers on the road.