Towing Calculators
Cargo placement.
Enter the trailer weight and tongue weight before loading, the axle-to-coupler distance and a load's weight and position, and get the new tongue weight, the axle load and the position that would hit your target tongue percentage. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Tongue weight changes by the load's weight times its distance ahead of the axle, divided by the axle-to-coupler distance. Putting 600 lb four feet ahead of the axle on a 12 ft trailer adds 600 x 4 / 12 = 200 lb to the tongue; putting it four feet behind the axle takes 200 lb off.
Worked example
A 4,000 lb trailer has a 400 lb tongue (10%) and 12 ft from axle to coupler. Add 600 lb at 4 ft ahead of the axle: tongue = 400 + 600 x 4 / 12 = 600 lb on a 4,600 lb total, or 13.0%. The axle carries the other 4,000 lb. To land exactly 12% (552 lb) the load would go about 3.0 ft ahead of the axle.
How it works
Moment balance about the axle: tongue = T0 + w x d / L. T0 is the tongue weight before the load, w the load, d its distance ahead of the axle (negative behind) and L the axle-to-coupler distance. The weight not carried by the tongue is carried by the axle(s), so the axle load is the total minus the tongue. The distance unit cancels, so feet or metres give the same answer.
This treats the trailer as a rigid beam resting on the axle and the coupler. It ignores suspension flex and, for tandems, assumes the axle group acts at its midpoint. Too little tongue weight can let the trailer sway and too much can cause problems for the tow vehicle; 10 to 15 percent of the loaded trailer is the usual guideline (see the tongue weight calculator). Weigh the result: this is arithmetic, not a measurement.
Sources opened 2026-10-16: Towing - Wikipedia (tongue weight and sway); static moment balance (basic mechanics); target band from the Trailer Tongue Weight Calculator. Planning aid only, not professional, engineering or safety advice. Your vehicle, trailer, hitch and boat manuals and the weight labels on your equipment come first; when in doubt, weigh it at a public scale or ask a qualified professional.
FAQ
Where should I put weight on a trailer?
Heavy items go low and close to the axle, with enough ahead of it to keep tongue weight in the usual 10 to 15 percent band. Items behind the axle reduce tongue weight.
How does cargo position change tongue weight?
Weight ahead of the axle adds to the tongue by its weight times distance divided by the axle-to-coupler distance. Weight behind the axle subtracts by the same rule.
What happens if the load is too far back?
Insufficient tongue weight can cause the trailer to sway back and forth when towed. Move heavy items forward of the axle.
What if the load is too far forward?
Too much tongue weight can cause problems with the tow vehicle, including payload and rear axle overload. Move cargo back toward the axle.
Does this work for tandem-axle trailers?
Yes, measure from the middle of the axle group to the coupler. It is an approximation, so verify with a tongue scale.