TowingMath

Weight Distribution Hitch Calculator

A WD hitch does not remove tongue weight. It moves load back onto your front axle. This shows how much of it you are actually recovering.

Three front axle weights

Loaded as you drive it, trailer not attached.
Trailer coupled, spring bars not tensioned.
Spring bars tensioned to your current setting.
Front axle load restored —

Enter your numbers above.

Verify before you tow. These figures are a planning aid, not professional or engineering advice. Your real limits are the ones printed on your vehicle's door-jamb placard, your trailer's VIN plate, and your owner's manual - and those override anything calculated here. When numbers are close, weigh the rig and go with the more conservative answer.

The formula

Front axle drop = Front (alone) - Front (hitched, bars off)

Restored        = Front (hitched, bars on) - Front (hitched, bars off)

Percent restored = (Restored / Front axle drop) x 100

Common target: at least 50% restored.
Many manufacturers specify 100% - back to the unhitched figure.
Your owner's manual governs.

Worked example

Front axle, truck alone           3,200 lb
Front axle, hitched, bars off     2,900 lb
Front axle, hitched, bars on      3,140 lb

Drop            = 3,200 - 2,900 = 300 lb
Restored        = 3,140 - 2,900 = 240 lb
Percent restored = (240 / 300) x 100 = 80%

80% restored, which clears the 50% rule comfortably. If the manufacturer of this truck specifies full restoration, add tension - another 60 lb of front axle load would bring it back to 3,200 lb.

What the hitch is and is not doing

The spring bars act as levers against the trailer frame, applying an upward moment at the coupler that rotates load off the rear axle and redistributes it forward to the tow vehicle's front axle and rearward onto the trailer's axles. Nothing gets lighter. Tongue weight is unchanged and still counts fully against payload - which is worth being clear about, because "the hitch takes care of it" is a common and expensive misunderstanding.

Common questions

How much weight does a weight distribution hitch distribute?

A weight distribution hitch does not remove tongue weight - it moves where that weight lands. The spring bars apply leverage that transfers part of the load off the tow vehicle's rear axle and back onto its front axle and the trailer's axles.

In practice a properly adjusted setup restores most or all of the front axle weight the trailer took away. The tongue weight itself is unchanged, and it still counts fully against your payload.

How do I know if my weight distribution hitch is adjusted correctly?

Weigh the front axle three times: tow vehicle alone, then coupled with the bars off, then coupled with the bars tensioned. Coupling drops the front axle weight; the bars should bring it back.

The common target is to restore the front axle to at least 50% of the drop, and many manufacturers specify returning it fully to the unhitched figure. Your tow vehicle's owner manual is the authority - follow it over any general rule, including this one.

When do I need a weight distribution hitch?

Most tow vehicle manufacturers require one above a stated trailer weight or tongue weight, often around 5,000 lb of trailer weight or 500 lb of tongue weight, though the threshold varies by vehicle. Exceeding it without a WD hitch can reduce your permitted tow rating.

The symptom to watch for is the rear squatting and the front end feeling light. That is front axle load being levered away, and it costs steering and braking authority exactly when you have the most weight to stop.

Does a weight distribution hitch increase towing capacity?

It can raise the rating of the hitch receiver itself - many Class III receivers carry a higher weight-distributing rating than weight-carrying rating, and both are on the receiver label.

It does not raise your vehicle's GVWR, GCWR, payload or axle ratings. Those are unchanged. A WD hitch fixes weight distribution, not weight.

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