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Trailer Tongue Weight

Free Trailer Tongue Weight calculator with clear step-by-step results.

About Trailer Tongue Weight

Tongue weight should be roughly 10% of loaded trailer mass - too little and the trailer will snake at speed, too much and it unloads the tow vehicle's front axle. The adjustment figure tells you how much load to move, and the lever arm converts that into how far cargo needs to shift.

Formulas

Target tongue weight

Target = loaded trailer mass x target percentage

Cargo shift

Moving mass m by distance d changes tongue weight by m x d / axle-to-coupling distance

Worked example

With the default values below, Trailer Tongue Weight returns Target tongue weight of 180.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Loaded trailer massminimum 10 kg
1,800 kg
Target tongue weightaccepts 3–25 %
10 %
Measured tongue weightminimum 0 kg
140 kg
Towball vertical load ratingminimum 1 kg
150 kg
Distance from axle to couplingminimum 0.2 m
3.2 m

Results

Target tongue weight
180.0 kg
Measured tongue weight as a share of trailer mass
7.78% %
Adjustment needed at the coupling
40.0 kg
Verdict
Within the safe range

Step by step

  1. 1Values used
  2. 2Target tongue weight
  3. 3Cargo shift
  4. 4Target tongue weight= 180.0 kg
  5. 5Measured tongue weight as a share of trailer mass= 7.78 %
  6. 6Adjustment needed at the coupling= 40.0 kg
  7. 7Verdict= Within the safe range

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Trailer loading and tongue weight are safety-critical and legally regulated. Weigh the coupling load, respect the towball and vehicle vertical load limits, and follow the trailer manufacturer's loading instructions.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Trailer loading and tongue weight are safety-critical and legally regulated. Weigh the coupling load, respect the towball and vehicle vertical load limits, and follow the trailer manufacturer's loading instructions.

Frequently Asked Questions

What happens if tongue weight is too low?

The trailer becomes directionally unstable and can begin to oscillate, or snake, at speed. Recovery is difficult and jackknifing is a real risk.

Can I exceed the towball rating if the trailer is within its limit?

No. The vertical load rating is an independent limit set by the towbar and vehicle, and exceeding it is both unsafe and illegal.

Related Calculators

Trailer Tongue Weight – Calculate Target tongue weight