Weight Distribution Hitch Setup Calculator
Enter an unhitched tow-vehicle ticket, a coupled ticket with the spring bars loose, and a coupled ticket with the bars engaged. The calculator estimates actual tongue weight, front axle load restoration, where the load moved, and whether the tested setup is above or below the selected front-axle target.
Front axle adjustment to target0
- Actual tongue weight
- 800
- Loaded trailer weight
- 6,400
- Tongue-weight percentage
- 12.5%
- Front axle load restoration
- 50%
- Weight restored to front axle
- 150
- Weight removed from rear axle
- 280
- Weight transferred to trailer axles
- 130
- Target front axle weight
- 3,250
- Front GAWR margin
- 650
- Rear GAWR margin
- 680
- Tow vehicle GVWR margin
- 530
- Trailer axle rating margin
- 1,270
- GCWR margin
- 2,600
- Scale-ticket consistency check
- The two hitched gross totals are within 0 lb, inside the 60 lb scale-ticket tolerance.
- Rating status
- All entered ratings have nonnegative margin on the bars-engaged ticket.
Scale-ticket totals and load movement
| Check | Value |
|---|---|
| Unhitched tow vehicle weight | 6,000 |
| Bars-disengaged gross combination weight | 12,400 |
| Bars-engaged gross combination weight | 12,400 |
| Hitched gross-total difference | 0 |
| Load-transfer balance difference | 0 |
Use the same passengers, cargo, fuel level, hitch hardware, and trailer load for all three weighings.
The trailer must stay coupled during both hitched weighings; only spring-bar tension should change.
How to use this calculator
- Weigh the loaded tow vehicle by itself with the same people, fuel, cargo, and hitch hardware that will be used for towing.
- Couple the trailer with the weight-distribution bars disengaged, then record the front, rear, and trailer axle-platform weights.
- Engage the bars at the adjustment you want to test, weigh the same combination again, and enter those three axle weights.
- Enter only the restoration target and ratings specified for your tow vehicle, trailer, receiver, and hitch hardware.
How the hitch setup is calculated
This calculator treats the three scale tickets as one audit. Let UF and UR be the unhitched front and rear axle weights. Let CF, CR, and CT be the coupled front, rear, and trailer-axle weights with the spring bars disengaged. Let DF, DR, and DT be the same three weights with the bars engaged.
The unhitched tow-vehicle weight is U = UF + UR. Actual tongue weight from the scale tickets is TW = CF + CR - U. Loaded trailer weight is LTW = CF + CR + CT - U, so tongue-weight percentage is 100 * TW / LTW when both values are positive.
Front axle load restoration compares the front-axle weight lost when the trailer was coupled to the amount restored by the engaged hitch. Front load lost is L = UF - CF. Restored load is R = DF - CF. The restoration percentage is 100 * R / L. If L is zero, the percentage is undefined; if L is negative, the tickets are atypical because the coupled front axle is heavier before the bars are engaged.
The target front weight is solved from the selected manufacturer target: TF = CF + target * L. The adjustment result is TF - DF. A positive number means the tested setup is below the selected front-axle target; a negative number means it is above that target.
What moves when the bars are engaged
The bars do not make tongue weight disappear. They change how the coupled load is carried. The calculator reports front load restored as DF - CF, rear load removed as CR - DR, and load transferred to the trailer axles as DT - CT. Ideally, rear load removed is close to front load restored plus trailer-axle load added, allowing for scale rounding.
The two hitched gross combination totals should also stay close because the same tow vehicle, trailer, occupants, fuel, cargo, and hitch hardware should be on the scale for both hitched tickets. A difference over 60 lb is flagged because it can mean changed loading, position error, fuel use, or ordinary scale uncertainty larger than expected.
What this calculator leaves out
The rating checks are simple margins against the bars-engaged ticket: front GAWR minus front axle weight, rear GAWR minus rear axle weight, GVWR minus the tow-vehicle axle sum, trailer axle rating minus trailer-axle weight, and GCWR minus gross combination weight. A zero rating input omits that check.
This tool does not choose the correct restoration target for a specific vehicle. Use the tow-vehicle owner's manual and hitch manufacturer's instructions. It also does not assess receiver compatibility, spring-bar rating, hitch-head angle, sway control, tire capacity, wheel capacity, side-to-side loading, or mechanical condition.
Worked example
Suppose the unhitched tow vehicle weighs 3,400 lb on the front axle and 2,600 lb on the rear axle, so U = 6,000 lb. Coupled with the bars loose, the tickets read 3,100 lb front, 3,700 lb rear, and 5,600 lb on the trailer axles. Actual tongue weight is 3,100 + 3,700 - 6,000 = 800 lb. Loaded trailer weight is 3,100 + 3,700 + 5,600 - 6,000 = 6,400 lb, so tongue weight is 12.5%.
With the bars engaged, the front axle reads 3,250 lb, the rear reads 3,420 lb, and the trailer axles read 5,730 lb. Front load lost from coupling was 3,400 - 3,100 = 300 lb, and the hitch restored 3,250 - 3,100 = 150 lb. That is 50% front axle load restoration. With a 50% target, the target front axle weight is 3,250 lb, so the front axle adjustment to target is 0 lb.
Common questions
How do I get the three scale tickets needed for this calculator?
Use one ticket for the loaded tow vehicle by itself, one ticket for the coupled combination with the weight-distribution bars disengaged, and one ticket for the same coupled combination with the bars engaged. Keep the same passengers, fuel, cargo, hitch hardware, and trailer load for all three tickets.
What is front axle load restoration?
Front axle load restoration compares the front-axle weight lost when the trailer is coupled to the amount brought back by the weight-distribution hitch. A 50% result means the bars restored half of the front-axle load that was removed by coupling the trailer without distribution.
Should my target be 0%, 50%, or 100% FALR?
Use the target specified by the tow-vehicle manufacturer and the hitch instructions. Different vehicles and model years can call for different restoration limits, and a generic calculator cannot override those instructions.
How is tongue weight calculated from scale tickets?
With the spring bars disengaged, add the tow vehicle front and rear axle weights, then subtract the unhitched tow vehicle weight. That difference is the actual trailer load carried by the tow vehicle at the coupler for that loading condition.
Why does a weight-distribution hitch add weight to the trailer axles?
Spring-bar tension creates leverage between the tow vehicle and trailer frame. Some load comes off the tow vehicle rear axle and is carried by the tow vehicle front axle and the trailer axles instead.
Can weight distribution increase towing capacity or payload?
No. A weight-distribution hitch can redistribute load, but it does not increase GVWR, GAWR, GCWR, receiver rating, tire rating, wheel rating, hitch rating, or trailer rating. Negative margins should be treated as over-rating conditions for the entered tickets.