Forklift Load Capacity Calculator
See how far a load center past the rated one cuts your forklift’s safe capacity, and the derated figure to plan around.
Derated safe capacity
Capacity is derated in proportion to load center: safe capacity = rated × (rated load center ÷ actual load center), rounded down to the kilogram. A closer load center does not license carrying more than the data-plate rating, so the recommended figure is capped there. An attachment adds its thickness to the load center and its weight comes off the capacity; a truck fitted with one needs the manufacturer’s revised data plate. Lift height can reduce capacity further. This is a planning estimate — the truck’s capacity data plate is the authority.
Why load center changes everything
A capacity rating is not a single number — it is a number tied to a load center. Move the center of gravity farther from the fork face and the same weight exerts a bigger tipping moment on the front axle, which is the pivot the whole truck balances over. Push that moment past what the counterweight can hold and the rear wheels start to lift.
That is why a truck rated to lift 2,500 kg at a 500 mm load center can carry no more than about 1,785 kg once the load center reaches 700 mm, and less again with an attachment fitted or at height. Long, deep, or unevenly packed loads are the usual culprits — and the reason capacity has to be checked against the actual load, not just the plate.
Frequently Asked Questions
How does load center reduce a forklift's capacity?
A forklift is rated to lift a set weight at a standard load center — the horizontal distance from the fork face to the load's center of gravity, commonly 500 mm (24 in). When the center of gravity sits farther out, the load exerts more tipping moment about the front axle for the same weight. Because moment is weight times distance, the safe weight drops in proportion: safe capacity = rated capacity × (rated load center ÷ actual load center).
What is the standard load center on a capacity plate?
Most counterbalance forklifts are rated at a 500 mm (about 24 in) load center for loads up to a certain height. Some plates quote 600 mm or use inch values. Always read the actual figure from your truck's data plate, because the rated capacity only holds at that specific load center.
Why does the calculator cap safe capacity at the rated value?
The moment formula gives a higher number when the load center is closer than rated, but a closer load center does not license carrying more than the plate rating. The mast, hydraulics, tilt cylinders, and frame all have their own limits set by the manufacturer, so the recommended safe figure is never allowed to exceed the data-plate rated capacity.
Does load height change the derated capacity too?
Yes. Capacity plates often list a reduced rating for lifting above a certain height, and attachments (side-shifters, clamps, extensions) shift the load center and add their own weight. This calculator adds an attachment's thickness to the load center and takes its weight off the capacity as a planning estimate, but a truck fitted with an attachment must carry the manufacturer's revised data plate, and for high lifts use the reduced figures on the plate. Those figures govern.
Is this a substitute for the truck's capacity data plate?
No. It is a planning estimate to help you understand how load center affects capacity. The truck's capacity data plate — with the operator trained and certified to read it — is the authority for any actual lift.
Estimates for planning — not professional safety, OSHA, or operator-certification advice. Follow the truck’s capacity data plate and get trained and certified before operating.