Forklift forks are not all the same. If you need to replace them, add attachments, or understand what is on your machine, you will have to match specific measurements: thickness, width, and length.
How Fork Dimensions Are Expressed
Dimensions are typically listed in a standard order: Thickness x Width x Length. For example, a common Class II fork might be expressed as 1 ½” x 4” x 42” or in millimeters as 40 x 100 x 1200.
The mounting system is standardized. Most modern forklifts use ITA (Industrial Truck Association) hook-type forks, which latch onto horizontal bars on the carriage. This design allows forks to be swapped between different trucks as long as the "Class" matches.
1. Fork Thickness
Thickness is measured along the vertical shank (the back of the fork). It is the most critical factor in determining lifting capacity. Generally, a thicker fork means a higher capacity.
ITA Class Typical Thickness (in) Typical Thickness (mm) Approx. Capacity Range
Class II 1 ½” – 1 ¾” 40 – 45 mm ~3,500 – 5,500 lbs
Class III 1 ¾” – 2” 45 – 50 mm ~5,500 – 11,000 lbs
Class IV 2” – 2 ½” 50 – 65 mm ~11,000 – 17,600 lbs
Class V 2 ½”+ 65 – 75 mm+ ~17,600 – 24,200 lbs
citation:
2. Fork Width
Width is measured across the face of the horizontal blade. The width must fit between the truck's mast channels and match the carriage class. Standard warehouse forks (Class II) are typically 4 inches (100–120 mm) wide, while larger industrial forks require 5–6 inches (122–150 mm).
3. Fork Length
Length is measured from the tip of the fork to the vertical heel. Picking the right length is about balancing stability with maneuverability.
Standard for Pallets: 42 inches (1070 mm). This fits standard 48" pallets cleanly without sticking out too far.
Rule of Thumb: The fork should extend at least two-thirds of the load's depth. For heavier loads in open yards (Class IV/V), lengths of 60 to 120 inches (1500–3000 mm) are common.
Capacity vs. Dimensions (Reference Table)
You cannot judge a fork's capacity by size alone, but these figures provide a useful benchmark.
Capacity Typical Size (T x W) Class Typical Length
1.5 - 2.5T 35 x 100 mm Class II 900 - 1100 mm
3.0 - 3.5T 45 x 122 mm Class III 1000 - 1200 mm
5.0T 50 x 150 mm Class III/IV 1200 - 1500 mm
8.0T - 10.0T 60 - 75 x 150 mm Class IV/V 1200 - 1800 mm
citation:
4. Fork Cross-Section
Most standard forks have a rectangular cross-section. However, specialized applications require different shapes:
Tapered/Tulip Forks: Wider at the heel and narrower at the tip. Common for lumber handling where precise entry into tight stacks is needed.
Hooked or Hinged Forks: Feature a hinged trailing section. Used for high-tip operations, such as emptying bins.
Fork Sleeves/Extensions: Square tube sections that slide over existing forks to add length for oversized loads.
Summary
If you are measuring an existing fork, the sequence is Thickness × Width × Length (e.g., 40×120×1070 mm). Always ensure the fork's ITA Class matches your forklift's carriage class. Never assume two forks are the same based solely on length.