How to Measure Your Forklift for Fork Extensions

Fork extensions must be correctly matched to the forks already fitted to your forklift truck. Ordering by forklift make or model alone is not always enough, because fork dimensions can vary between trucks and replacement forks may have been fitted during the machine's working life.

The key measurements are straightforward: fork length, fork width and fork thickness. You should also confirm the required extension length, the type of load being handled and whether the forklift has sufficient capacity for the load at the extended load centre.

This guide explains exactly how to measure your forklift forks before ordering extensions, how the commonly used 150% sizing rule works and which details to send us if you would like the fitment checked.

To compare the sizes currently available, view our complete range of forklift fork extensions.

What Measurements Do You Need for Fork Extensions?

Before choosing a pair of extensions, record the following information:

• The length of the existing forklift forks.
• The width of each fork blade.
• The thickness of each fork blade.
• The extension length you intend to use.
• The forklift's rated capacity and stated load centre.
• The approximate dimensions and weight of the load.

The first three measurements determine whether the extensions will physically fit the forks. The remaining information helps establish whether the proposed setup is suitable for the intended load.

Equipment Needed to Measure Forklift Forks

You do not need specialist measuring equipment. In most cases, the following will be sufficient:

• A reliable tape measure.
• A steel rule or vernier calliper for checking thickness accurately.
• A pen and paper or phone for recording the dimensions.
• A clear photograph of the forks and heel area.
• The forklift's capacity plate or data plate information.

Record all dimensions in millimetres. Using one unit consistently reduces the risk of confusing measurements when requesting a quotation or comparing extension specifications.

Step 1: Park and Prepare the Forklift Safely

Before taking measurements, park the forklift on firm, level ground in a suitable area away from moving vehicles and normal site traffic.

Lower the forks until they are safely supported close to the ground, apply the parking brake, place the controls in neutral and isolate the truck in line with your workplace procedure. Do not attempt to measure moving or raised forks.

Remove loose dirt or material that could affect the measurement, particularly around the top and sides of the fork blade.

Step 2: Measure the Fork Length

Fork length is measured along the horizontal blade, from the front face of the fork heel to the tip.

The heel is the inside bend where the vertical shank transitions into the horizontal fork blade. Place the tape measure against the front face of this heel and run it straight along the top surface to the furthest point of the fork tip.

Do not measure:

• From the forklift carriage.
• From the rear of the vertical fork shank.
• Around the curved profile of the heel.
• Only the exposed portion beneath a pallet.

Common fork lengths include approximately 1,000mm, 1,200mm and 1,500mm, but you should always measure the actual forks rather than relying on an assumed standard size.

Step 3: Measure the Fork Width

Fork width is measured across the horizontal top face of one fork blade.

Place the tape measure or steel rule across the fork from one side edge to the other. Take the measurement on a straight and undamaged section of the blade rather than at the tapered tip.

Measure both forks. They should normally match, but checking both can reveal whether a replacement fork, damaged fork or mismatched pair is fitted.

Typical examples include fork sections such as:

• 80mm wide.
• 100mm wide.
• 125mm wide.
• 150mm wide.
• 200mm wide.

The extension must have sufficient internal clearance to slide over the fork, but it should not be so oversized that it can move excessively during operation.

Step 4: Measure the Fork Thickness

Fork thickness is measured vertically through the horizontal blade.

Use a steel rule or calliper at the full-thickness section of the blade, away from the tapered tip. Measure from the underside of the fork to the upper surface.

Common fork sections are normally described as width by thickness. For example:

• 80 x 40mm means 80mm wide and 40mm thick.
• 100 x 50mm means 100mm wide and 50mm thick.
• 125 x 50mm means 125mm wide and 50mm thick.
• 150 x 60mm means 150mm wide and 60mm thick.

Do not reverse the two figures when submitting your measurements. Always write the width first and the thickness second unless a supplier specifically requests a different format.

Step 5: Measure Both Forks

Even when both forks appear identical, check each one separately.

Look for:

• Different widths or thicknesses.
• Visible twisting or bending.
• Excessive wear along the heel or underside.
• Damage that may prevent the extensions sliding on correctly.
• Previous repairs or alterations.

Fork extensions should not be used to disguise damage or compensate for forks that are no longer in a serviceable condition. Any concern about fork condition should be assessed by a competent person before an attachment is fitted.

Step 6: Apply the Fork-Extension 150% Rule

A widely used sizing rule is that the overall length of a fork extension should not exceed 150% of the length of the original forklift fork.

Put another way, the original fork should support at least two-thirds of the extension's total length.

This calculation establishes an upper limit rather than automatically identifying the best size. Choose the shortest extension that provides adequate support for the intended load while remaining suitable for the forklift and operating environment.

For more help with extension length, construction and load type, read our guide to choosing forklift fork extensions.

Step 7: Measure the Load You Need to Handle

Measuring the forks confirms which extensions can fit the truck. Measuring the load helps determine how long those extensions actually need to be.

Record the load dimension running in the same direction as the forks. This might be the depth of an oversized pallet, the width of a timber pack or the supported length of a fabricated component.

The aim is to provide suitable support without selecting unnecessarily long extensions. Excessive extension length moves the load further from the mast, affects manoeuvrability and can reduce the forklift's available capacity.

Fork extensions are most appropriate for long, stable loads that can be properly supported. Examples include:

• Oversized pallets.
• Timber packs.
• Steel sections.
• Roofing materials.
• Plastic pipe bundles.
• Packaged construction materials.

To understand the applications they are designed for, see our article on when to use forklift fork extensions.

Step 8: Check the Forklift Capacity Plate

Correct physical fitment does not confirm that the forklift can safely lift the proposed load.

Fork extensions position part of the load further forward than the original forks. As the load centre increases, the forklift's effective lifting capacity can decrease.

Record or photograph the forklift's data plate, including:

• The forklift make and model.
• The rated lifting capacity.
• The stated load centre.
• The permitted lift height.
• Any existing attachment or derated capacity information.

You should also establish the approximate weight and centre of gravity of the load. Do not assume that a forklift rated to lift a particular weight at its standard load centre can lift the same weight safely when longer extensions move the load further forward.

Where the data plate does not cover the intended configuration, obtain advice from a competent person or the forklift supplier before use.

Step 9: Check the Extension Retention Method

Fork extensions should include a suitable method of retaining them on the forks, commonly a heel pin or retaining mechanism positioned behind the fork heel.

Before ordering, inspect the heel area and make sure:

• The retention system can be fitted correctly.
• There is no obstruction preventing secure engagement.
• The heel and fork structure are in sound condition.
• The extensions can be installed and removed without forcing them.

Never operate extensions without the supplied retention system properly fitted. The extensions must not be free to slide off the fork tips during travel or when the forks are tilted.

Standard Measurement Example

Imagine that your measurements are:

• Fork length: 1,200mm.
• Fork width: 100mm.
• Fork thickness: 50mm.
• Required extension length: 1,800mm.

The fork section would be recorded as 100 x 50mm. Under the 150% calculation, a 1,200mm original fork can normally support an extension up to 1,800mm long.

That does not complete the suitability check. You would still need to confirm the weight and dimensions of the intended load, the forklift's capacity at the revised load centre and the suitability of the selected extension model.

For regular industrial use on 100 x 50mm or 125 x 50mm forks, view our heavy-duty forklift fork extensions. For more demanding applications or a wider range of fork sections, compare our ultra-heavy-duty fork extensions.

Heavy Duty vs Ultra Heavy Duty Fork Extensions

The correct model depends on more than its length.

Heavy-duty extensions can be suitable for regular handling applications where the fork section and required extension length match the available specification. Ultra-heavy-duty extensions provide a reinforced option for more intensive environments, denser loads or larger fork sections.

Do not select an ultra-heavy-duty model simply because it sounds safer. The extension must still fit the forks correctly, suit the load and remain within the forklift's permitted capacity.

Common Fork-Measurement Mistakes

Measuring from the carriage instead of the heel

Fork length starts at the front face of the heel and ends at the fork tip. Including the vertical shank or carriage creates an inaccurate measurement.

Measuring only one fork

Both forks should be checked. A previous replacement or hidden damage may mean they are not identical.

Measuring at the tapered tip

The fork becomes narrower and thinner near the tip. Width and thickness should be measured on the full-section part of the horizontal blade.

Confusing width and thickness

A 100 x 50mm fork is normally 100mm wide and 50mm thick. Reversing these measurements can result in the wrong sleeve size being supplied.

Ordering from the forklift model alone

The truck may have several compatible fork options or replacement forks fitted. Measure the physical forks rather than relying solely on a handbook or model number.

Ignoring the original fork length

An extension may fit over the fork section but still be too long in relation to the supporting fork.

Choosing the longest possible extension

Longer is not automatically better. Select the shortest suitable extension that provides the load support required.

Checking fit but not forklift capacity

Correct sleeve dimensions do not establish safe lifting capacity. The changed load centre must also be considered.

Fork-Extension Measurement Checklist

Use this list before requesting a quotation:

• Forklift make and model: ____________________
• Existing fork length: ____________________ mm
• Fork width: ____________________ mm
• Fork thickness: ____________________ mm
• Required extension length: ____________________ mm
• Forklift rated capacity: ____________________ kg
• Rated load centre: ____________________ mm
• Approximate load weight: ____________________ kg
• Load dimensions: ____________________
• Material or load type: ____________________
• Frequency of use: occasional / regular / intensive

Photographs of the forks, heel area, forklift data plate and intended load can also help confirm the correct option.

Frequently Asked Questions

How do I measure the length of a forklift fork?

Measure in a straight line along the horizontal blade from the front face of the fork heel to the furthest point of the tip. Do not start from the carriage or rear of the vertical shank.

How do I measure fork width and thickness?

Measure width horizontally across the top face of the blade and thickness vertically from the underside to the upper surface. Take both measurements on the full-section part of the fork, away from the tapered tip.

What does a 100 x 50mm forklift fork mean?

It normally means the fork blade is 100mm wide and 50mm thick. Fork extensions must have internal dimensions suitable for that fork section.

Can I choose fork extensions using the forklift model?

The model is useful supporting information, but the actual forks should still be measured. Fork options vary, and replacement forks may have been fitted.

What is the 150% rule for fork extensions?

It means the overall extension length should normally be no more than 150% of the original fork length. For example, a 1,200mm fork would allow an extension up to 1,800mm under this rule.

Can fork extensions be slightly wider than the forks?

Some clearance is required so the extension can slide over the fork, but excessive clearance may result in poor fit and movement. Select an extension specifically designed for the measured fork section.

Do fork extensions reduce forklift lifting capacity?

They can reduce the forklift's effective capacity because the load is positioned further from the mast. Check the forklift's rating at the relevant load centre and obtain competent advice where required.

Should I measure both forklift forks?

Yes. Confirm that both forks have matching dimensions and are free from damage or excessive wear before fitting extensions.

What information should I send when asking for fork extensions?

Provide the fork length, width and thickness, required extension length, forklift make and model, capacity information, load dimensions and approximate load weight.

Should fork extensions support the entire load?

The load must be adequately and evenly supported, but the exact suitability depends on its construction, weight, centre of gravity and the forklift's capacity. Fork extensions should not be used as a substitute for a proper load assessment.

Choose the Correct Fork Extensions for Your Truck

Accurate measurements prevent ordering delays and help ensure that the extensions fit securely over the existing forks.

Start by measuring the original fork length from heel to tip. Then measure the width and thickness of both blades at their full section. Apply the 150% rule to establish the maximum extension length, and check the intended load and forklift capacity before making a final selection.

Browse our full range of forklift fork extensions or use our fork-extension selection guide to compare the other factors involved.

For a broader look at the available equipment, read our complete guide to forklift attachments or explore the full forklift attachments range.

If you are unsure which model will fit, submit the measurements from the checklist above through our request a quote page. Include photographs of the forks and data plate where possible, and we can help identify the most suitable option.