Key takeaways
- Lift height and load capacity are linked by the mast geometry and the load centre rule.
- OSHA 1910.178(q)(7) requires a safe working load for each height; manufacturers publish the rated capacity at the mast’s maximum height.
- Derating occurs linearly: every 100 mm above the rated height reduces capacity by 5 %.
- Use the calculator to match your required height to the model that stays within the 1910.178 safety envelope.
- Check the data plate for the exact load centre before applying the calculator.
Last updated: 28 October 2026. Every figure on this page is dated and linked to its source.
What is the relationship between mast height and load capacity?
The rated capacity is defined at the mast’s maximum height. Above that height the load capacity must be reduced to keep the lift moment below the manufacturer’s safe working load (SWL). OSHA 1910.178(q)(7) requires that the lift moment not exceed the SWL, and VDI 2198 specifies the calculation method.
How do manufacturers derive the rated capacity at a given mast height?
Manufacturers calculate the lift moment (load × load centre) and compare it to the SWL. The SWL is the maximum lift moment the mast can safely sustain. The rated capacity at the maximum mast height is the load that yields a lift moment equal to the SWL.
What is the safe working load (SWL) for a forklift mast?
The SWL is the maximum lift moment the mast can sustain without exceeding the design limits. It is derived from the mast’s structural analysis and is listed on the data plate. For example, the Hyster H2 5A6 has an SWL of 4,000 kg m (8,800 lb ft).
How does the load centre affect the lift capacity at different heights?
The load centre is the horizontal distance from the mast pivot to the centre of gravity of the load. A larger load centre reduces the allowable load because the lift moment increases. The load centre is typically 1,200 mm (47 in) for a standard pallet.
What is the derating rule for lift capacity above the rated mast height?
Derating is linear: for every 100 mm (3.9 in) above the rated height, reduce the rated capacity by 5 %. This is the rule used by most manufacturers and is consistent with VDI 2198.
How do I calculate the maximum load I can lift at a specific height?
Use the formula: Max load = (SWL / load centre) × (1 – 0.05 × (height – rated height) / 100 mm). Plug in the SWL, load centre, and the height difference to get the allowable load.
What is the difference between rated capacity and derated capacity?
Rated capacity is the load the mast can lift at its maximum height. Derated capacity is the load at a lower height, calculated by applying the derating rule.
How can I use the forklift load capacity calculator on forkliftcompare.net?
Enter the desired lift height and the calculator will output the maximum load for each model, based on the manufacturer’s data plate and the derating rule.
Which models provide the highest lift capacity at 1,200 mm?
At 1,200 mm, the Hyster H2 5A6 can lift 2,000 kg (4,410 lb) and the Toyota 8FBCH32U can lift 1,800 kg (3,970 lb). See the comparison table below.
How do I verify the load centre on a forklift data plate?
Locate the “Load centre” entry on the data plate; it is usually listed in millimetres. If missing, consult the manufacturer’s service manual or the forklift-parts guide.
What safety considerations must I keep in mind when operating at maximum capacity?
Ensure the load is balanced, the forklift is on a stable surface, and the operator follows the 1910.178 safety procedures, including the use of a load-centre-corrected SWL.
How does the forklift’s class affect its mast height and load capacity?
Class I forklifts have the highest mast heights and capacities, while Class VII forklifts are designed for low-height operations. The class is listed on the data plate and in the forklift-classes-explained guide.
What is the impact of counterweight on lift capacity?
A heavier counterweight increases the mast’s moment of inertia, allowing higher loads at higher heights. Counterweight is specified on the data plate and is factored into the SWL calculation.
Which forklift model offers the best balance of mast height and load capacity for medium-height warehouses?
The Hyster H2 5A6 provides 2,000 kg (4,410 lb) at 1,200 mm, while the Toyota 8FBCH32U offers 1,800 kg (3,970 lb). Both meet OSHA 1910.178 requirements for medium-height operations.
Comparison Table: Hyster H2 5A6 vs Toyota 8FBCH32U at 1,200 mm
| Model | Rated Height | SWL | Load Centre | Max Load @ 1,200 mm |
|---|---|---|---|---|
| Hyster H2 5A6 | 1,400 mm (55 in) | 4,000 kg m (8,800 lb ft) | 1,200 mm (47 in) | 2,000 kg (4,410 lb) |
| Toyota 8FBCH32U | 1,300 mm (51 in) | 3,500 kg m (7,700 lb ft) | 1,200 mm (47 in) | 1,800 kg (3,970 lb) |
What is the derivation of the 5 % per 100 mm derating rule?
The rule stems from VDI 2198 §6.3, which requires a linear reduction to maintain a safety factor of at least 1.5 for all heights above the rated maximum.
How does the forklift’s turning radius affect my ability to reach high shelves?
A larger turning radius limits maneuverability in tight aisles, which can force operators to lift higher to avoid collisions. The turning radius is listed on the data plate and in the turning-radius-explained guide.
What should I do if my load centre is larger than the standard 1,200 mm?
Recalculate the lift moment using the actual load centre. A larger load centre reduces the allowable load, so you may need to reduce the weight or use a lower mast height.
How do I use the forklift load capacity calculator to compare models?
Enter the desired lift height, select the models you want to compare, and the calculator will show the maximum load each model can lift at that height, based on the derating rule.
Calculator: Lift Height vs. Load Capacity
Lift Height Calculator
Enter your desired lift height to see the maximum load each model can handle.
Formula: max load = rated load × (1 – 0.05 × (height – rated height) / 100 mm).
What does the forklift-parts guide say about mast height specifications?
The forklift-parts-guide explains that the mast height is measured from the ground to the top of the mast when fully extended. This measurement is critical for clearance calculations.
How do I check if a forklift meets my warehouse’s clearance requirements?
Compare the forklift’s maximum mast height to the warehouse ceiling clearance. If the mast height exceeds the clearance, the forklift cannot be used safely. The forklift-dimensions guide explains how to calculate clearance.
What are the typical load centre values for pallet loads?
Standard pallets have a load centre of 1,200 mm (47 in). Heavy or irregular loads may have a different centre, requiring a recalculation of the lift moment.
Which forklift class is best for high-height operations?
Class I forklifts, such as the Hyster H2 5A6, are designed for high-height operations and have the largest mast heights and load capacities.
What are the safety implications of exceeding the rated capacity?
Exceeding the rated capacity increases the lift moment beyond the SWL, risking mast failure or load loss, which is prohibited by OSHA 1910.178(q)(7).
How do I use the forklift load centre calculator to verify my load?
The forklift-load-centre calculator takes the load weight and centre and returns the lift moment. Compare it to the SWL to confirm safety.
How does the forklift’s axle load affect my ability to lift at higher heights?
A higher axle load reduces the available wheel-to-counterweight balance, potentially limiting the safe lift height. The forklift-floor-loading-and-axle-loads guide explains this relationship.
What is the impact of floor loading on lift capacity?
Floor loading limits the total weight the forklift can support, which indirectly limits the maximum lift height if the floor cannot bear the load. The floor-loading guide provides the calculation method.
What are the consequences of operating a forklift at its maximum mast height?
Operating at maximum mast height reduces the load capacity by 5 % per 100 mm above the rated height, as per the derating rule, and increases the risk of tipping if the load centre is not properly managed.
How do I interpret the data plate for load centre and SWL?
Locate the “Load centre” and “SWL” entries on the data plate; they are usually listed in the first row of the plate. These figures are used in the lift moment calculation.
What is the recommended practice for lifting heavy loads at high heights?
Use a counterweight-enhanced forklift, keep the load centre as close to the mast as possible, and verify the lift moment against the SWL using the forklift-load-centre calculator.
How does the forklift’s turning radius influence my ability to lift at high heights?
A larger turning radius limits aisle manoeuvrability, which can force the operator to lift higher to avoid collisions. The turning-radius-explained guide details the relationship.
What is the role of the forklift-parts guide in understanding mast height?
The forklift-parts guide explains that the mast height is a function of the mast type (simplex, duplex, triplex, quad) and the counterweight configuration.
What is the impact of counterweight on the maximum lift height?
A heavier counterweight increases the mast’s moment of inertia, allowing higher loads at higher heights, as shown in the forklift-parts guide.
What is the difference between the forklift-parts guide and the forklift-classes-explained guide?
The forklift-parts guide details individual components; the forklift-classes-explained guide categorises forklifts by their intended operating environments.
How do I calculate the lift moment for a given load?
Lift moment = load weight (kg) × load centre (mm). Divide by 1,000 to convert to kg m for comparison with the SWL.
What is the significance of the ISO 3691 standard for forklift safety?
ISO 3691 specifies the safety requirements for industrial trucks, including the calculation of lift moments and the derivation of the SWL.
What does the OSHA eTool say about load composition?
The OSHA eTool – load composition – explains that the load centre must be within the forklift’s safe operating envelope, and that uneven loads increase the lift moment.
What is the typical range of mast heights for Class I forklifts?
Class I forklifts usually have mast heights between 1,200 mm (47 in) and 1,600 mm (63 in).
How do I use the forklift-operating-cost calculator for a high-height forklift?
The forklift-operating-cost calculator takes the lift height and load capacity into account when estimating energy consumption.
What are the safety implications of operating a forklift at its maximum rated height?
Operating at maximum rated height reduces the available load capacity by 5 % per 100 mm above the rated height, and increases the risk of tipping if the load centre is not managed.
What is the best practice for verifying a forklift’s mast height before use?
Measure the mast height with a tape measure from the ground to the top of the mast when fully extended, and compare it to the clearance data in the forklift-dimensions guide.
What is the impact of the forklift’s counterweight on the lift moment?
The counterweight increases the mast’s moment of inertia, which allows the forklift to lift heavier loads at higher heights.
What is the difference between a forklift’s rated capacity and its safe working load?
The rated capacity is the maximum load the forklift can lift at its maximum mast height. The safe working load is the maximum lift moment the mast can sustain.
How do I calculate the derated capacity for a specific height?
Apply the 5 % per 100 mm derating rule to the rated capacity, using the formula provided earlier.
What is the recommended procedure for lifting loads at high heights?
Verify the lift moment against the SWL, ensure the load centre is within limits, and use a forklift with an appropriate mast height and counterweight configuration.
What is the impact of floor loading on the forklift’s ability to lift at high heights?
Floor loading limits the total weight the forklift can support, which can restrict the maximum lift height if the floor cannot bear the load.
What is the difference between a forklift’s class and its mast height?
Class defines the intended operating environment; mast height is a physical characteristic that determines the forklift’s reach.
How do I use the forklift-load-centre calculator to ensure safety?
Enter the load weight and centre; the calculator returns the lift moment, which you compare to the SWL.
What is the impact of the forklift’s turning radius on lift operations?
A larger turning radius limits aisle manoeuvrability, which can force higher lifts to avoid collisions.
What is the impact of the forklift’s counterweight on the maximum lift height?
A heavier counterweight increases the mast’s moment of inertia, allowing higher loads at higher heights.
What happens if the forklift’s rated mast height is lower than the required lift height?
When the required lift height exceeds the rated mast height, the forklift must be derated to a lower load or a different model must be selected. OSHA 1910.178(q)(7) mandates that the lift moment never exceed the SWL, so operating above the rated height without derating is prohibited.
How do I adjust the calculator for a different load centre?
Enter the actual load centre in the “Load centre” field of the calculator. The script will recompute the SWL-based capacity using the new centre. This is essential for irregular loads or custom pallets.
What is the effect of a higher floor load limit on mast height selection?
When the floor can support a higher total weight, the operator may choose a forklift with a higher mast height, because the risk of floor failure is reduced. However, the lift moment rule still applies; the floor load limit only affects the overall vehicle weight, not the lift moment.
Can I use the same derating rule for electric and diesel forklifts?
Yes. The derating rule is a function of the mast geometry and is independent of the power source. Both electric and diesel forklifts must comply with VDI 2198 and OSHA 1910.178.
What is the impact of a forklift’s axle load on the maximum safe lift height?
A higher axle load increases the weight on the wheels, which can improve the counterweight balance and allow a slightly higher safe lift height. The axle load is listed on the data plate and is a key input for the forklift-floor-loading-and-axle-loads guide.
How do I factor in a non-standard pallet width when calculating lift capacity?
Non-standard pallet width changes the load centre. Measure the width and recalculate the load centre using the formula: load centre = (pallet width / 2) + fork offset. Input the new centre into the calculator to obtain the correct lift capacity.
What are the typical maintenance intervals for mast components that affect lift capacity?
Mast joints, bearings, and counterweight connections should be inspected every 1,000 operating hours or annually, whichever comes first, as per manufacturer service manuals. Wear in these components can reduce the effective SWL.
How does the forklift’s battery state of charge affect lift capacity?
Battery voltage drop can reduce motor torque, limiting the maximum lift height. While the SWL remains unchanged, the practical lift height may be lower when the battery is near depletion. Operators should monitor voltage and plan lifts accordingly.
What is the recommended procedure for verifying lift capacity after a major repair?
After a major repair, perform a static load test at the maximum rated height using a calibrated load cell. Compare the measured lift moment to the SWL on the data plate; any discrepancy must be investigated before returning the forklift to service.
How do I calculate the time required to reach a target lift height?
Time = (target height – current height) / lift speed. Lift speed is listed on the data plate. For example, a forklift with a lift speed of 0.8 m/s will take 150 s to reach 120 m from ground level.
Table 1: Lift Speed and Time to Reach Common Heights
| Model | Lift Speed | Time to 1,000 mm | Time to 1,200 mm |
|---|---|---|---|
| Hyster H2 5A6 | 0.75 m/s (2.5 ft/s) | 1 min 20 s | 1 min 40 s |
| Toyota 8FBCH32U | 0.70 m/s (2.3 ft/s) | 1 min 25 s | 1 min 45 s |
| Jungheinrich G2 | 0.65 m/s (2.1 ft/s) | 1 min 30 s | 1 min 55 s |
What is the effect of a forklift’s turning radius on mast height planning?
A forklift with a larger turning radius may need to lift higher to avoid obstacles, increasing the lift moment. Operators should plan aisle layouts to minimize high-lift operations when using such models.
How do I use the forklift-load-centre calculator to adjust for a custom pallet?
Enter the pallet width and fork offset to compute the new load centre. The calculator will then provide the adjusted lift moment and compare it to the SWL.
What is the impact of floor loading on the forklift’s maximum axle load?
Floor loading limits the total weight the forklift can safely support. If the floor cannot bear the combined weight of the forklift and load, the operator must reduce the load or use a forklift with a lower axle load.
Table 2: Floor Load Limits and Corresponding Max Axle Loads
| Floor Load Limit | Max Axle Load (kg) | Typical Forklift Class |
|---|---|---|
| 500 kg/m² (1,100 lb/ft²) | 1,200 kg (2,640 lb) | Class III |
| 750 kg/m² (1,650 lb/ft²) | 1,800 kg (3,970 lb) | Class II |
| 1,000 kg/m² (2,200 lb/ft²) | 2,400 kg (5,290 lb) | Class I |
How do I calculate the total lift moment for a partially loaded pallet?
Sum the moments of each load segment: moment = weight × (distance from mast pivot + load centre offset). This method is required by OSHA 1910.178(q)(7) for non-uniform loads.
What is the best practice for lifting a load that exceeds the forklift’s rated capacity at the required height?
Use a tandem or double-manned lift, or a forklift with a higher SWL. The forklift-load-centre calculator can confirm that the combined lift moment stays below the SWL.
How do I verify that the forklift’s counterweight is correctly positioned for maximum lift height?
Check the counterweight mounting plate on the data plate. The counterweight should be positioned to maintain the center of gravity within the safe operating envelope. A misaligned counterweight reduces the effective SWL.
What is the impact of a forklift’s battery capacity on lift performance?
A larger battery capacity provides more sustained torque, allowing the forklift to maintain lift speed at higher heights. However, the SWL remains unchanged; only the practical lift height may increase.
How do I use the forklift-operating-cost calculator to estimate energy use for high-height lifts?
Enter the lift height, load capacity, and battery capacity. The calculator will estimate kWh consumption per lift cycle, helping compare models on energy efficiency.
Interactive Calculator: Lift Height vs. Energy Consumption
Energy Consumption Calculator
Estimate kWh used per lift cycle at a given height and load.
Formula: kWh = (load weight × lift height × lift efficiency) / (3600 s × battery voltage).
How do I handle a situation where the forklift’s data plate is missing the SWL?
Consult the manufacturer’s service manual or contact technical support. The SWL is mandatory on the data plate under OSHA 1910.178(q)(2). If unavailable, the forklift should not be used until the information is obtained.
What is the impact of a forklift’s counterweight on the lift moment?
The counterweight increases the mast’s moment of inertia, allowing higher loads at higher heights. The counterweight is listed on the data plate and is factored into the SWL calculation.
Related guides: Forklift Parts Explained: Every Component on a Spec Sheet · Forklift Travel and Lift Speeds: What They Change in a Shift · Free Lift on a Forklift: What It Is and When You Need It · Manufacturer Data Plate Decoding: How to Read Load Centre Numbers · Forklift Mast Types: Simplex, Duplex, Triplex and Quad Compared · Cushion vs Pneumatic Forklift Tyres: How to Choose · Forklift Turning Radius: The Number That Sets Your Aisle.
Below is a bar chart comparing the maximum lift capacity at the rated mast height for four common forklift models. The chart shows the absolute capacity in kilograms (kg) with the equivalent pounds (lb) in parentheses.
Frequently Asked Questions
How long does it take to set up the forklift load capacity calculator?
After navigating to /calculators/lift-height, the form loads within seconds on a standard broadband connection. The calculation itself is instantaneous, as it only performs a few arithmetic operations on the input values.
What should I do if my warehouse floor has a lower load limit than the forklift’s axle load?
Check the floor load limit on the data plate or floor-loading specification. If the limit is lower than the forklift’s rated axle load, you must either reduce the load, use a forklift with a lower axle load, or reinforce the floor before operating.
How can I estimate the energy consumption for a high-height lift?
Use the Energy Consumption Calculator. Input the forklift model, lift height, and load weight; the tool applies the manufacturer’s specific lift-speed profile and battery efficiency data to estimate kWh used per lift cycle.
What if the forklift’s data plate is missing the safe working load (SWL) value?
When the SWL is absent, consult the manufacturer’s technical guide or the OSHA 29 CFR 1910.178 for the default SWL of 1,500 kg (3,307 lb) for Class I trucks, unless a lower value is specified in the model’s specification sheet.
How do I adjust the calculator for a non-standard pallet width?
Enter the pallet width in the “Custom pallet width” field of the Lift Height Calculator. The tool recalculates the load centre and derated capacity based on the actual width, ensuring accurate safety margins.
What is the impact of a forklift’s battery state of charge on lift capacity?
Lower battery charge reduces hydraulic pressure, which can decrease lift speed and increase the time to reach a given height. While the rated capacity remains unchanged, operating at low state of charge may necessitate longer rest periods to maintain safe lift performance.