Forklift fork thickness is a critical specification that determines how much weight a fork can safely handle. It is measured along the vertical shank (the back of the fork) or at the heel (the curved area where the blade meets the shank). Thicker forks are required for higher lifting capacities and heavier loads.
Standard Fork Thickness by ITA Class
Fork thickness varies by ITA carriage class, which corresponds to the forklift's lifting capacity.
ITA Class Carriage Height Capacity Range Typical Fork Thickness
Class I 13.03 inches Less than 2,000 lbs Less than 1.25 inches
Class II 16.00 inches 2,000 – 5,500 lbs 1.4 – 1.75 inches
Class III 20.00 inches 5,501 – 11,000 lbs 1.75 – 2.0 inches
Class IV 25.00 inches 11,000 – 17,500 lbs 2.0 – 2.5 inches
Class V 28.66 inches 17,500 – 24,000 lbs 2.0+ inches
Class II forks are the most common for standard warehouse forklifts. A standard Class II fork is typically 1.4" to 1.7" thick when brand new. The most common thickness overall is 1½ inches, with other standard sizes including 1¾", 2", and 2½".
Real-World Examples (Crown Forks)
| Class | Dimensions (Thickness × Width × Length) | Capacity |
| :--- | :--- | :--- | :--- |
| Class II | 1.75" × 4" × 48" | 5,500 lbs |
| Class III | 1.75" × 5" × 60" | 6,000 lbs |
The Critical Safety Limit: 10% Heel Wear
The heel of the fork is the most common point of wear. Over time, friction between the fork and the floor wears down the thickness at this critical point.
The 10% Rule: A fork must be removed from service when heel wear exceeds 10% of its original thickness.
Example: A fork with an original thickness of 1.75 inches must be replaced when the heel wears down to 1.575 inches (1.75 × 0.90).
A worn fork will not hold the load the forklift is rated to lift, leading to product damage and serious injury. Fork-wear calipers are used to identify excessive wear.
How to Measure Fork Thickness
Fork thickness is measured along the heel (the curved area) or the vertical shank. Use a caliper or a dedicated fork-wear caliper to measure the thickness at the heel, where wear is most concentrated. Compare the measurement to the fork's original specification. If the thickness has been reduced by more than 10%, the fork must be withdrawn from service.
Other Fork Dimensions
Fork dimensions are typically expressed in the order Thickness × Width × Length.
Dimension Measurement Location Common Values
Thickness Along the heel or shank 1.25" – 2.5"+
Width Across the face of the blade Class II: 4"; Class III: 5"; Class IV: 6"
Length From the tip to the face of the heel 42", 48", 60"
The Bottom Line
Fork thickness increases with ITA class and lifting capacity. Class II forks range from 1.4" to 1.75" thick; Class III forks are typically 1.75" to 2.0"; Class IV forks range from 2.0" to 2.5". The critical safety limit is 10% heel wear—exceeding this reduces the fork's structural integrity and requires immediate replacement. Always measure thickness with a caliper at the heel and compare to the original specification.