Forklifts are indispensable in warehouses, construction sites, and logistics operations—but they also present serious safety risks if not used correctly. One of the most overlooked but critical aspects of forklift safety is calculating load sizes accurately.
Whether you’re operating a counterbalance forklift or a high-reach warehouse reach truck, understanding load sizes, weight distribution, and capacity limits is essential. In this article, we’ll walk through how to determine if a load is safe to lift, why your forklift’s rating plate matters, how lift height changes everything, and why professional guidance is sometimes the best decision you can make.
Why Load Size Calculation Is Essential for Safe Forklift Operation
Accidents Happen When You Guess
It’s easy to assume a forklift can lift any pallet it can fit between its forks—but this assumption can be dangerous. very forklift is rated for specific capacities at specific conditions, including weight, load centre, and lift height. A slight variation in any of these factors can drastically reduce the machine’s stability.
According to occupational safety data, incorrect load handling is a major cause of tip-overs, dropped loads, and injuries on warehouse floors. And the risks multiply when using specialised equipment like reach trucks, which are often used to lift heavy pallets to significant heights.
Rating Plates Are More Than Just Stickers
Every forklift comes with a rating plate (also known as a data plate) mounted somewhere visible on the chassis. This plate shows the maximum rated capacity of the machine, including:
- The weight it can lift safely.
- The lift height that capacity applies to.
- The load centre distance assumed in the calculation.
Ignoring this plate—or failing to understand how to interpret it—can lead to disastrous results.
Understanding Forklift Load Basics
Load Weight and Load Centre: A Balancing Act
Let’s say your forklift is rated to lift 2,000 kg at a 500 mm load centre. That doesn’t mean it can safely lift any 2,000 kg load. The “load centre” refers to the horizontal distance from the face of the forks to the load’s centre of gravity.
If your load is unusually long or top-heavy, its centre of gravity may shift further out. This increases the leverage on the mast and reduces the effective capacity of your forklift.
This is especially relevant when operating reach trucks, which are designed for deep reach into racking and lifting at heights where load centre and weight become even more critical.
Load Dimensions and Lift Height Affect Capacity
When you lift a load higher, your forklift’s centre of gravity rises and shifts. The higher the lift, the lower your safe working capacity. For instance, a reach truck rated to lift 1,500 kg at 3 metres might only lift 1,000 kg safely at 7 metres.
Always consult the load capacity chart (usually found on the rating plate or in the forklift manual) to check how height and load size impact what your forklift can actually handle.
Reach Trucks: Precision Lifting Requires Precision Planning
What Makes Reach Trucks Different?
Reach trucks are engineered for high-density, narrow-aisle environments. They’re built to reach deeper into racking systems and lift loads higher than traditional forklifts. While this makes them indispensable for warehousing, it also means they operate on tighter margins when it comes to load capacity and balance.
Because of their tall masts and narrow footprint, load calculations must be even more precise. Even a small deviation in load centre or weight can cause a reach truck to become unstable when lifting.
Learn more about reach truck types and capabilities in our Reach Truck Forklift Guide.
How to Read a Reach Truck Rating Plate
Rating plates on reach trucks typically list:
- Maximum lift capacity at a standard lift height (e.g., 1,200 kg at 4,000 mm).
- De-rated capacities at various lift heights.
- Recommended load centre distances.
For non-standard loads or when stacking at the highest points in your racking system, refer to this plate and adjust accordingly. If unsure, reach out to your supplier or a qualified materials handling expert.
Step-by-Step: How to Calculate Your Load Size for a Forklift or Reach Truck
Determine the Weight of the Load
- Use a scale or check the bill of lading to confirm total weight.
Measure the Load Centre
- For square pallets, this is typically 500 mm. For larger items, find the midpoint of the load’s depth.
Check the Load Dimensions
- Note the height, width, and depth—especially if the load is unusually shaped or tall.
Assess Lift Height
- How high will you need to raise the load? Higher lifts reduce safe capacity.
Consult the Rating Plate
- Cross-check your measurements against the forklift’s capacity chart.
Adjust Your Load or Method if Needed
- Split oversized loads, lower lift heights, or switch to a higher-capacity reach truck if necessary.
Real-World Scenarios: When Load Calculation Matters Most
Scenario 1: Tall, Light Load on a Reach Truck
A warehouse operator needs to lift a 400 kg but 2.5-metre-tall pallet to a 9-metre shelf. Even though the load is light, its centre of gravity is high, increasing the chance of tipping. The solution? Use a reach truck with stabilising outriggers and ensure the rating plate confirms safe operation at the needed height.
Scenario 2: Oversized Load on Standard Forklift
A 1,800 kg generator with a load centre of 700 mm is being loaded with a forklift rated for 2,000 kg at 500 mm. The extended load centre puts the actual load outside the safe range. The fix? Recalculate capacity with the actual load centre or use a forklift with longer forks and higher de-rated capacity.
When to Get Expert Help
While understanding how to calculate your load sizes is crucial, the safest path is often to consult a professional—especially when dealing with:
- Non-uniform or irregular loads.
- High-rack warehouse layouts.
- Heavier loads at extreme lift heights.
- New or unfamiliar reach truck models.
At Criterion, we specialise in helping businesses select the right equipment and understand the exact specs of their operational needs. If you’re ever unsure about load sizing or reach truck suitability, contact us for guidance.
Conclusion: Safe Lifting Starts with Smart Calculation
Calculating your forklift or reach truck load sizes isn’t just about following regulations—it’s about protecting your staff, your inventory, and your bottom line. By understanding the interplay between load weight, centre, height, and equipment capacity, you’ll operate smarter and safer.