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Of all the safety risks in forklift operation, load capacity is among the most frequently misunderstood. Many operators know that there is a maximum load rating for a forklift, but fewer understand that this rating is highly context-dependent: it changes with mast tilt, lift height, load dimensions, attachment type, and load centre. Operating a forklift at or beyond its effective capacity in real conditions can cause tip-overs, dropped loads, and serious or fatal injuries.
This guide explains the key concepts of forklift load capacity so that operators and fleet managers can apply them correctly. Mars Forklifts supplies forklifts to businesses across Sydney and the east coast, including training on safe operation as part of equipment induction.
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The Load Plate: Where to Start
Every forklift has a load plate, typically mounted at or near the operator station in a position clearly visible during operation. The load plate specifies the rated capacity of the forklift, typically in kilograms, and critically, the conditions under which that rating applies. A load plate is not a single number: it is a table of capacities at different lift heights and load centre distances.
What Is Load Centre?
The load centre is the horizontal distance from the face of the forks to the centre of gravity of the load. Most standard forklift capacity ratings are based on a load centre of 600mm (sometimes written as 600mm LC). This assumes a load with its centre of gravity 600mm back from the face of the forks.
When a load’s centre of gravity is further than 600mm from the face of the forks (a deeper pallet, a large but lightweight item that extends well forward), the effective capacity of the forklift decreases. This is because the load creates greater leverage on the front axle (the forklift’s tipping fulcrum), reducing the effective load the forklift can safely carry without tipping forward.
| Load centre | Effect on capacity |
| 600mm (standard rating) | Full rated capacity applies |
| Greater than 600mm | Effective capacity is reduced: the load plate shows reduced capacity figures for extended load centres |
How Lift Height Affects Capacity
Lifting a load raises its centre of gravity, which affects the stability of the forklift. For counterbalance forklifts and reach trucks, the rated capacity typically decreases as lift height increases, because the elevated load creates greater instability risk. The load plate shows different capacity figures at different lift heights.
A forklift that can safely carry 2,500kg at ground level may only be rated for 1,800kg when the load is elevated to four metres. Operators who lift loads to maximum racking height without accounting for the reduced capacity at height are operating outside safe parameters.
How Attachments Affect Capacity
Forklift attachments including side-shifters, paper roll clamps, slip-sheet attachments, drum handlers, and rotators all affect the effective capacity of the forklift for two reasons: they add weight that counts against the rated capacity, and they change the effective load centre by extending the load further forward from the face of the forks.
When an attachment is fitted, the load plate for the attachment must be consulted in addition to the forklift’s load plate, because the attachment changes the capacity calculation. Using a forklift with an attachment without accounting for the attachment’s effect on capacity is a common and serious error.
The Stability Triangle
Counterbalance forklifts operate on a stability triangle defined by the three contact points with the ground: the two front wheels and the rear axle pivot. When a loaded forklift is operating within its rated capacity and recommended operating conditions, the combined centre of gravity of the forklift and load remains within this triangle, maintaining stability.
When the load is too heavy, the load centre is too long, or the forklift is travelling on uneven ground with a raised load, the combined centre of gravity can move outside the stability triangle. At this point, the forklift tips forward. A forward tip-over with an operator in an open cab is one of the most common causes of serious forklift fatalities.
Common Capacity Errors to Avoid
- Estimating load weight: never assume or estimate. Load weight must be known and confirmed against the load plate before lifting. Unknown loads should be weighed or confirmed by documentation before the forklift operator lifts them
- Ignoring lift height: applying the ground-level capacity rating to loads being lifted to racking height. Check the load plate for the capacity at the specific lift height required
- Forgetting attachment weight and load centre effect: when any attachment is fitted, the forklift capacity changes. Refer to the attachment load plate as well as the forklift load plate
- Travelling with elevated loads: a forklift should travel with the load lowered as close to the ground as is practical. Travelling with an elevated load raises the centre of gravity and dramatically increases tip-over risk, particularly on slopes or uneven surfaces
💡 Reach trucks have different capacity considerations: Reach trucks are designed for narrow-aisle racking operation and have different capacity and stability characteristics from counterbalance forklifts. The load plate for a reach truck must be consulted specifically, and operators must be trained on the specific model. Do not assume that reach truck capacity and stability behave the same as a counterbalance forklift.
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Frequently Asked Questions
What happens if a forklift tips over?
A forklift tip-over is one of the most serious incidents in warehouse and industrial operations. In a forward tip-over, an operator in an open cab who tries to exit the machine is at risk of being crushed under the overhead guard. Forklift operators are trained to stay in the seat and hold on in the event of an imminent tip-over, because the overhead guard is designed to protect the operator when they remain in the cab.
Who is responsible for ensuring forklift loads are within capacity?
Both the operator and the business have WHS obligations relating to safe load operation. The operator is responsible for confirming that loads are within the rated capacity before lifting and for refusing to lift loads that are of unknown or excessive weight. The business (PCBU) is responsible for providing operators with the information and procedures needed to confirm load weights, and for ensuring that the load plate is present and legible on all forklifts.
