How to calculate truck axle load distribution (step-by-step guide)

A truck can be perfectly within its overall weight limit and still be illegal to drive — if the cargo is positioned in a way that overloads a single axle. Gross vehicle weight and axle load are two different checks, and most load planning mistakes that result in roadside fines come from confusing the two.

This guide walks through exactly how axle load distribution is calculated, the legal limits in the EU and US, and what it actually costs when a load gets it wrong.

Axle load vs gross vehicle weight — the distinction that causes most violations

Gross vehicle weight (GVW) is the total weight of the truck and everything in it. Axle load is how that total weight is shared between the truck’s individual axles. A truck can sit comfortably under its GVW limit while still having one axle — usually the drive axle, if cargo is loaded too far toward the rear — over its individual legal limit.

This is the single most common cause of axle violations: planners check the total weight, confirm it’s under the limit, and assume the load is legal. The axle distribution is a separate calculation entirely.

How the calculation works — the lever principle

Picture the cargo area as a simple beam, supported at two points: the front axle and the rear (drive) axle. Every item placed in that space pulls down on the beam at its own position, and that pull is shared between the two support points based on how close the item sits to each one.

Front axle contribution = Item weight × (distance from item's CoG to rear axle) ÷ axle span
Rear axle contribution  = Item weight - Front axle contribution

Worked example: a 1,000kg item with its centre of gravity exactly halfway between a front axle at position 100cm and a rear axle at position 1,100cm (a 1,000cm span).

The item is equidistant from both axles, so the load splits evenly: 500kg to the front axle, 500kg to the rear axle.

If the same item is placed with its centre of gravity directly over the rear axle instead, the rear axle carries the full 1,000kg and the front axle carries none of it — even though total vehicle weight hasn’t changed at all.

This is why two loads with identical total weight can have completely different legality — distribution matters as much as total weight.

Don’t forget the vehicle’s own weight

The truck’s unladen weight also contributes to each axle and must be added before checking against legal limits. This is typically split unevenly between front and rear — for a loaded semi-trailer, a common approximation is around 40% of unladen weight on the front axle and 60% on the rear, though the exact split varies by vehicle configuration and should be confirmed against your specific vehicle’s specifications where precision matters.

EU and US legal limits

*US gross vehicle weight limits vary by axle spacing under the federal bridge formula — 36,287 kg (80,000 lbs) is the commonly cited general limit, but exact figures depend on your specific axle configuration.

What overloading actually costs

The financial consequence of an axle violation goes well beyond the base fine. In the United States, total costs for a single overweight axle violation — including the fine itself, unloading and reloading fees, detention charges while the load is corrected, and missed delivery penalties — can reach $16,000 in the most severe cases. Even a “minor” overage can mean an unplanned delay, a missed delivery window, and the cost of correcting the load at the roadside or a nearby facility.

How to fix an overweight axle without removing cargo

The fastest fix is redistribution, not removal. Moving heavy items toward the centre of the wheelbase reduces the load on both end axles. Moving items away from an overloaded axle and toward the axle with spare capacity reduces the overloaded one without changing the total vehicle weight at all. Only when redistribution alone cannot bring every axle within its limit does cargo actually need to come off the truck or move to a second vehicle.

Checking this automatically

Calculating this by hand for every shipment is slow and easy to get wrong, especially with mixed cargo positioned at different points along the load. Most dedicated axle calculators are standalone tools — you enter a static configuration manually, separate from your actual cargo plan. Teuvia’s free truck axle load calculator checks compliance the same way, but as part of a full container and truck load plan: as you place items in 3D, axle distribution is calculated automatically against both EU and US limits, with no separate tool or manual re-entry required. If you are planning the cargo itself, the same workspace includes our container loading calculator.