How to use this calculator
- Enter empty weights. Use the trailer weight and measured tongue weight before adding the cargo groups below.
- Measure hitch-to-axle distance. Measure from the hitch ball or coupler to the center of the trailer axle group.
- Enter cargo locations. Enter each cargo group weight and its center-of-gravity distance from the hitch.
- Set the target range. Use the default 10-15% target range or enter the range you are screening against.
- Review load shift. Check tongue percent, axle-group load and the CG shift needed to reach the target midpoint.
How it works
The calculator models the hitch and trailer axle group as the two static
supports. Each cargo group changes tongue load by its weight times the
support-reaction lever:
dT = W x (1 - x/L)
where x is the cargo CG distance from the hitch and L
is the hitch-to-axle-group distance. Cargo centered ahead of the axle adds
tongue load; cargo centered behind the axle can unload the hitch.
Total tongue weight is: T = T_empty + sum(dT_i) and trailer CG from the hitch is: xCG = L x (1 - T/W_total) Use the result with the truck axle load calculator or truck payload calculator because tongue load counts against GVWR, axle ratings, tires and hitch limits.
Worked example
Verified against the live calculator
With a 2,000 lb empty trailer, 250 lb empty tongue
weight and a 12 ft hitch-to-axle distance, the default cargo
groups add 433 lb of tongue load. Gross trailer weight is
3,600 lb, tongue weight is 683 lb, and
tongue percent is about 19.0%. Against a 10-15% target
range, that is high, so the combined trailer CG would need to move rearward
toward the target midpoint before final scale checks.
Frequently asked questions
How do you calculate trailer tongue weight from load position?
Treat the hitch and axle group center as supports. A cargo item changes tongue load by W x (1 - x/L), where x is its center-of-gravity distance from the hitch and L is hitch-to-axle distance.
What tongue weight percentage should I use?
The calculator defaults to a 10-15% target range because that is a common planning window, but real trailers, hitches and load-distribution setups depend on manufacturer limits and measured scale weights.
Can cargo behind the axle reduce tongue weight?
Yes. When a cargo center of gravity is behind the axle group center, x is greater than L, so its contribution to tongue weight is negative.
Does this replace scale weights or towing ratings?
No. Use it as a static load-position screen. Real towing decisions need measured tongue weight, trailer axle weight, tire ratings, hitch and coupler ratings, weight-distribution guidance and manufacturer limits.
Method & assumptions
- The model is static and planar, with the trailer axle group collapsed to one support point.
- Cargo positions are center-of-gravity estimates measured from the hitch ball or coupler.
- It does not model sway stability, braking dynamics, suspension compliance, weight-distribution hitch behavior, tire load ratings, coupler ratings or tow-vehicle rear-axle geometry.
- Real towing decisions still need measured tongue weight, axle scale weights, tire ratings, hitch and coupler ratings, trailer manufacturer limits, tow-vehicle ratings and local legal requirements.