Drag · Add · Tune · Re-balance

Where you put the load decides what your hitch holds.

Pick up any cargo box and slide it down the trailer. Tongue weight, percent of GTW, and axle load update on every pixel of motion. Add a generator on the A-frame, two e-bikes on the rear bumper, or a full water tank — the math runs live.

Tow Vehicle

Specs that drive the lever arm

Vehicle

Curb weight lb

Wheelbase ft

Hitch overhang ft rear axle → ball

GVWR lb Front GAWR lb Rear GAWR lb GCWR lb Payload lb Max tongue lb

Find these numbers on the door-jamb sticker, in the owner's manual, or on the manufacturer's spec sheet for your trim level.

Truck Load

Passengers + bed cargo

No truck load yet — add passengers or bed cargo above.

Ratings Check

Live vs. manufacturer limits

Trailer Workbench

Drag cargo · scroll trailer params on the right

Drag any cargo · Tap to select · ←→ to nudge

Tongue Weight

—

% of GTW

—

target 10–15%

Axle Load

—

lb on trailer axle

Tongue % vs. industry target zone In safe zone

0% 10% • 15% 30%

Cargo ahead of axle

Adds tongue weight. The further forward, the bigger the lever arm — a 100 lb item 12 ft ahead of a 17-ft axle adds 71 lb to the hitch.

Cargo behind axle

Subtracts tongue weight. Bumper-mounted bikes, rear bunks, or anything past the axle pull the rig toward sway.

Sweet spot: 10–15%

Below 10% — sway risk on the highway. Above 15% — strains the tow vehicle's rear axle and degrades steering.

Use a real measurement

The dry tongue weight slider should reflect a CAT-scale or tongue-scale reading of your empty trailer — not the brochure number.

Trailer Setup

Measured dry baseline

Dry weight lb

Trailer length ft

Axle configuration

Coupler → axle ft

Dry tongue weight lb · 11.8%

The dry tongue weight should come from a CAT-scale or tongue-scale measurement of your empty trailer. It bakes in where the fridge, A/C, slide-out, and frame really sit — so you don't have to estimate the dry CG.

Weight-Distributing Hitch

Spring-bar tuning · FALR

Use weight-distributing hitch

Restores load to front axle

Front axle load restoration 100% FALR

Recommended bars: —

Effect summary

Front axle

+0 lb

Rear axle

−0 lb

Trailer axle

+0 lb

WDH improves load distribution but does not prevent sway. Add friction sway control or use an integrated anti-sway WDH (Equal-i-zer, Reese Strait-Line, ProPride) for sway management.

Cargo

Drag in scene · edit here

No cargo yet — add an item or pick a preset above.

Live Calculation

Updates as you drag

Industry guideline: keep tongue weight at 10–15% of Gross Trailer Weight. Below 10% invites sway; above 15% overloads the tow vehicle's rear axle. This calculator uses the lever-arm formula T = T_dry + Σ Wᵢ · (L_axle − Lᵢ) / L_axle — measured dry tongue weight plus each cargo item's signed lever-arm contribution. The truck axle model uses a sum-of-moments about the front axle: F_rear = (Σ W·x + T·(WB+OH))/WB, with tongue lifting T·OH/WB off the front. The WDH model adds a front-axle restoration +falr·T·OH/WB with 60% transfer relief from rear to trailer axle (simplified Reese / Husky / Equal-i-zer model). Always verify with a real scale before towing.

Where you put the load decides what your hitch holds.

Focused calculators