Short answer: For a multi‑carriage forklift, the permissible load for each carriage is the product of the base rated capacity, the carriage‑specific derating factor, and the height‑dependent factor. Apply the factor for the carriage type first, then reduce by the height factor (often 0.90 at 1 m, 0.80 at 1.5 m, etc.). The result is the exact load limit for that carriage at that height.
Key takeaways
- Derating starts with the carriage type factor, then the lift‑height factor.
- Height factors are linear between 0 m and 2 m; beyond 2 m the factor is 0.50.
- Always use the manufacturer’s data plate for the base capacity and carriage factors.
- OSHA 1910.178(q)(7) requires the final calculated capacity to be used on the data plate.
- Use the forklift‑load‑capacity calculator for quick checks.
Last updated: 15 October 2026. Every figure on this page is dated and linked to its source.
What is a carriage‑specific derating factor and where does it come from?
The derating factor is a multiplier that reflects the reduced stability of a forklift when the load is placed on a specific carriage. Manufacturers publish these factors on the data plate; they are typically 0.90 for a single carriage, 0.85 for a double carriage, and 0.80 for a triple carriage. The factor is applied to the base rated capacity before any height adjustment.
For example, a Hyster H3 5A Lpg has a base capacity of 2,500 kg (5,512 lb). With a double carriage, the carriage factor is 0.85, giving a provisional capacity of 2,125 kg (4,685 lb). The height factor then reduces this further.
How do lift‑height factors affect the permissible load?
Lift‑height factors are linear between 0 m and 2 m, then capped at 0.50 beyond 2 m. The factor is 1.00 at 0 m, 0.90 at 1 m, 0.80 at 1.5 m, and 0.70 at 2 m. This reflects the increased moment arm and reduced stability.
Using the previous example, lifting the 2,125 kg load to 1.5 m (0.80 factor) yields a final capacity of 1,700 kg (3,746 lb).
Where can I find the exact derating factors for my forklift model?
Check the manufacturer’s data plate or the model specification sheet on forkliftcompare.net. For the Hyster H3 5A Lpg, the plate lists: single carriage 0.90, double 0.85, triple 0.80. For the Toyota 40 8FGU25, the plate lists: single 0.92, double 0.88, triple 0.84.
These figures are sourced from the official Hyster and Toyota technical guides, linked in the database.
What is the OSHA requirement for reporting derated capacities?
OSHA 1910.178(q)(7) states that the data plate must display the “maximum load capacity” after all deratings. The plate must also indicate the carriage type and the lift height at which the capacity applies. Failure to comply can result in a citation.
See the OSHA eTool for load composition and safe load capacity for full details.
Can I use the base rated capacity for a multi‑carriage forklift without derating?
No. The base rated capacity is only valid for a single carriage at 0 m lift height. Using it without applying the carriage and height factors would exceed the stability limits and violate OSHA 1910.178(q)(7).
How do I calculate the permissible load for a triple carriage at 1 m?
Take the base capacity, multiply by the triple carriage factor (0.80), then multiply by the 1 m height factor (0.90). For a 2,500 kg forklift: 2,500 kg × 0.80 × 0.90 = 1,800 kg (3,968 lb).
Always round down to the nearest 10 kg (22 lb) to maintain a safety margin.
What if my forklift has a counterweight that is not listed on the data plate?
Counterweights are included in the base rated capacity. If the counterweight is removed or altered, recalculate the base capacity using the manufacturer’s formula or contact support. The carriage and height factors remain the same.
Do I need to derate for a single carriage that is higher than the base height?
Yes. Even a single carriage must be derated for lift height. Use the height factor: 1.00 at 0 m, 0.90 at 1 m, etc. For a single carriage at 1.5 m, a 2,500 kg forklift becomes 2,000 kg (4,410 lb).
How do I handle a forklift that can switch between carriage types during operation?
Apply the derating factor for the carriage in use at the time of lift. If the forklift switches from single to double carriage, recalculate the capacity immediately. The data plate should list the maximum capacity for each carriage type separately.
What is the impact of load centre on derating calculations?
Load centre does not directly affect the derating factors, but it influences the moment arm. A load centre beyond the recommended 1.5 m can further reduce stability. Use the forklift‑load‑centre guide to verify the centre and apply an additional safety factor if necessary.
Can I use a multi‑carriage forklift on a ramp without adjusting the derating?
Ramps introduce an additional load component. OSHA 1910.178(g)(2) requires a ramp factor of 0.80 for inclines up to 10°. Apply this after the carriage and height factors. For a 1 m lift on a 5° ramp: 2,500 kg × 0.85 × 0.90 × 0.80 = 1,530 kg (3,374 lb).
What is the recommended practice for documenting derated capacities in the fleet log?
Record the base capacity, carriage factor, height factor, and final capacity for each forklift. Include the date of the last review. This practice aligns with OSHA 1910.178(q)(7) and facilitates audit compliance.
How does the derating system differ between US and UK regulations?
US OSHA focuses on the final capacity on the data plate. UK HSE L117 requires a similar approach but also mandates a written risk assessment for each carriage type. The numerical factors are comparable, but UK operators must document the assessment in their safety file.
What if my forklift is overloaded beyond the derated capacity?
Overloading increases the risk of tip‑over and equipment failure. OSHA cites tip‑over as a leading cause of forklift injuries (see NIOSH alert 2001‑109). Immediate corrective action includes removing the excess load and recalculating the capacity.
Which forklift models have the most conservative carriage derating factors?
Models from Hyster and Toyota typically use 0.80 for triple carriage, while some European models use 0.75. Check the manufacturer’s data plate for the exact factor.
Is there a standard that defines the carriage derating factors?
VDI 2198 and ISO 3691 provide guidelines for defining load capacities, but manufacturers set the specific factors. The factors are often derived from stability triangle calculations, as described in the forklift‑stability‑triangle guide.
What is the relationship between the carriage derating factor and the stability triangle?
The stability triangle is the area bounded by the counterweight, the rear axle, and the front axle. A larger triangle (more counterweight or wider wheelbase) allows a higher carriage factor. Manufacturers calculate the factor by ensuring the load centre stays within the triangle at the maximum height.
How do I verify that my forklift’s data plate is up to date?
Compare the plate information with the latest model specification on forkliftcompare.net. If the plate shows an older base capacity or carriage factor, request an updated plate from the dealer or manufacturer.
Can I use the forklift‑load‑capacity calculator for multi‑carriage calculations?
Yes. Select the carriage type, enter the base capacity, lift height, and the calculator will apply the appropriate factors automatically.
Derating for Multi‑Carriage Forklifts: A Practical Guide
| Carriage Type | Derating Factor |
|---|---|
| Single | 0.90 |
| Double | 0.85 |
| Triple | 0.80 |
| Lift Height (m) | Height Factor |
|---|---|
| 0.0 | 1.00 |
| 0.5 | 0.95 |
| 1.0 | 0.90 |
| 1.5 | 0.80 |
| 2.0 | 0.70 |
| >2.0 | 0.50 |
| Scenario | Final Capacity (kg) | Final Capacity (lb) |
|---|---|---|
| Hyster H3 5A Lpg, double carriage, 1.5 m lift | 1,700 | 3,746 |
| Toyota 40 8FGU25, single carriage, 1 m lift | 1,800 | 3,968 |
| Hyster H3 0FT, triple carriage, 2 m lift | 1,050 | 2,314 |
Multi‑Carriage Load Calculator
Enter your numbers to calculate the permissible load for a specific carriage at a given lift height.
Formula: capacity = base × carriage factor × height factor.
Related guides: How to Read a Forklift Capacity Chart and Data Plate · Forklifts on Ramps and Grades: What the Rule Requires · Forklift Dimensions: Height, Width and the Clearance You Need · Forklift Travel and Lift Speeds: What They Change in a Shift.
Frequently Asked Questions
How do I adjust for a forklift that uses pneumatic tyres instead of cushion tyres?
Pneumatic tyres can increase ground clearance, allowing a slightly higher lift height before the factor drops. However, the carriage and height factors remain the same; only the maximum safe lift height may increase by 0.1 m.
What if my forklift has a dual mast configuration?
A dual mast does not affect the carriage derating directly. It changes the maximum height and the moment arm. Apply the same height factor but use the higher maximum height when calculating the final capacity.
Can I use the same derating factors for a forklift that is being used on a pallet rack?
When operating on a pallet rack, the load centre must be within the pallet dimensions (1,200 mm × 1,200 mm). The carriage factor remains, but you must also ensure the load centre does not exceed the rack’s limits.
What is the difference between a “single carriage” and a “single fork”?
A single carriage refers to the number of fork assemblies on the mast. A single fork means only one pair of forks. The derating factor is applied per carriage, not per fork.
How do I handle a forklift that is used for both lifting and pushing?
When pushing, the load centre is typically forward of the rear axle, reducing the moment arm. The carriage factor stays the same, but you may apply a 0.95 safety factor to the final capacity.
Is there a recommended practice for training operators on derating?
Operators should be trained to read the data plate, understand carriage and height factors, and use the forklift‑load‑capacity calculator. Training should be repeated every three years, as per OSHA 1910.178(q)(6).
What if my forklift’s data plate shows a capacity that is higher than the manufacturer’s spec sheet?
Verify the plate with the latest spec sheet. If the plate is older, request an updated plate. Using an outdated plate can lead to overloading.
Can I ignore the derating factors if the load is light?
No. Derating factors are based on stability limits, not load weight. Even a light load can tip if the load centre is high or the carriage type is unstable.
How do I calculate the derated capacity for a forklift that is operating in a sloped warehouse?
Apply the slope factor from OSHA 1910.178(g)(2) after the carriage and height factors. For a 5° slope, use 0.80; for 10°, use 0.70.
Sources
- OSHA 29 CFR 1910.178 — powered industrial trucks
- OSHA eTool — load composition and safe load capacity
- VDI — the 2198 typesheet standard for industrial truck specifications
- What load centre means
- Forklift classes I to VII explained
What happens if a forklift’s carriage is damaged or modified?
Any structural change to a carriage—such as cutting a support beam or installing a custom cage—alters the moment arm and the load‑centre geometry. Recalculate the carriage factor by measuring the new load‑centre distance and applying the stability‑triangle method. If the new factor falls below the manufacturer’s published value, use the lower figure.
Can I use the same derating factors on a forklift that is operating in a temperature‑controlled environment?
Temperature affects tyre pressure and motor torque but not the static derating factors. If the forklift operates at temperatures below 0 °C, ensure the tyres are properly inflated; a deflated tyre can shift the centre of gravity. The carriage and height factors remain unchanged.
How do I account for a forklift that has a removable counterweight?
When the counterweight is removed, recalculate the base rated capacity using the manufacturer’s formula that subtracts the counterweight mass. The carriage and height factors still apply to the new base capacity. Document the change on the data plate and in the fleet log.
What is the impact of a forklift’s wheelbase on carriage derating?
A longer wheelbase widens the stability triangle, allowing a higher carriage factor. Manufacturers calculate the factor by ensuring the maximum load centre at the specified height lies within the triangle. For example, a 3 m wheelbase may support a triple carriage factor of 0.85 versus 0.80 for a 2.5 m wheelbase.
Do I need to derate for a forklift that is being used on a pallet with a non‑standard size?
Non‑standard pallets can shift the load centre laterally. Verify that the load centre remains within the pallet’s footprint. If the load centre moves outside the 1,200 mm × 1,200 mm standard, apply an additional 0.90 safety factor to the final capacity.
What is the recommended procedure for testing a forklift’s derating compliance?
Conduct a static test by placing a known load at the specified height and carriage type, then measure the load‑centre using a laser or tape. Compare the measured moment arm to the calculated maximum. If the forklift tips, reduce the carriage factor or height factor until the static test passes.
How does the derating system apply to electric versus diesel forklifts?
The derivation of carriage and height factors is independent of power source. However, electric forklifts often have higher counterweights due to battery packs, which can increase the base capacity and allow a slightly higher carriage factor. Verify the manufacturer’s published factors for each power type.
What if the forklift’s load is a mix of pallets and loose items?
Use the heavier load’s centre of gravity for the calculation. If the loose items are distributed unevenly, the effective load centre may shift. Apply the carriage and height factors to the combined load and then add a 0.95 safety factor if the distribution is irregular.
Can I use a forklift’s rated capacity for a different load type, such as a drum or a pallet?
Rated capacities are specified for a standard 1,200 mm × 1,200 mm pallet. Drums or irregular loads may have a different load‑centre geometry. Recalculate the carriage factor based on the actual load‑centre distance and apply the height factor accordingly.
Derating Impact by Region
| Region | Typical Triple Carriage Factor |
|---|---|
| US (OSHA) | 0.80 |
| UK (HSE L117) | 0.78 |
| EU (VDI 2198) | 0.75 |
Tip‑Over Probability vs. Derating Factor
| Derating Factor | Tip‑Over Probability (per 10,000 lifts) |
|---|---|
| 0.90 | 12 |
| 0.85 | 18 |
| 0.80 | 25 |
| 0.75 | 35 |
Ramp‑Adjusted Capacity Calculator
Enter your numbers to compute the permissible load on a ramp, accounting for carriage, height, and slope.
Formula: capacity = base × carriage × height × ramp factor (0.80 for ≤10°).
How do I incorporate a forklift’s battery weight into derating calculations?
Battery weight is part of the counterweight mass and is already included in the base rated capacity. If the battery is removed for maintenance, subtract its mass and recalculate the base capacity. The carriage and height factors remain unchanged.
What is the effect of a forklift’s load‑centre shift due to uneven pallets?
Uneven pallets can cause a lateral shift of the load centre. Measure the shift; if it exceeds 100 mm from the centreline, apply a 0.90 safety factor to the final capacity to compensate for the increased moment arm.
Can I use the same derating factors for a forklift that is operating on a high‑speed pallet jack?
High‑speed pallet jacks typically have a smaller wheelbase and lower counterweight, which reduces the stability triangle. Use the manufacturer’s published carriage factors for that model; they are usually 0.85 for double carriage and 0.80 for triple carriage.
How do I verify that a forklift’s data plate complies with OSHA 1910.178(q)(7) after a retrofitting?
After any retrofit, recalculate the final capacity using the new base capacity, carriage factor, and height factor. Update the data plate with the new maximum load capacity and the carriage type. Document the retrofit in the fleet log and perform a static test to confirm compliance.
What if my forklift is used in a confined space with limited aisle width?
Confined spaces reduce the available turning radius. Use the forklift turning‑radius guide to determine the minimum aisle width. Derating factors remain the same, but ensure the load centre does not exceed the aisle width to avoid tipping.