---
title: "Overhead Crane Capacity: How to Choose the Right Tonnage"
description: "Overhead crane capacity explained: what counts towards the rated load, how to size it and what changes from 10 t to 100 t. Get the tonnage right first."
url: https://ervancranes.com/en/blog/overhead-crane-capacities/
language: en
---

**Overhead crane capacity** is the heaviest load a crane may lift, and it includes everything hung from the hook: slings, lifting beams, magnets or grabs. Size it from your heaviest real lift plus accessories and planned growth. Between 1 t and 100 t the design changes markedly – girder type, hoist, wheel loads and the demands on your building.

How capacity fits together with span and duty class is covered in our guide to [choosing an overhead crane by capacity, span and duty class](https://ervancranes.com/en/blog/choosing-an-overhead-crane-capacity-span-duty-class/); this article looks at capacity itself.

## What rated capacity actually covers

The rated capacity – also called rated load or safe working load (SWL) – is the maximum load the crane is designed to lift in normal operation and is marked clearly on the crane. The hook block and wire rope belong to the crane and are already allowed for in its design; everything you attach below the hook counts against the rated capacity:

- **Load-attaching gear:** slings, chains, shackles and eyebolts.
- **Lifting attachments:** lifting beams, spreaders, C-hooks, coil tongs, plate clamps and vacuum lifters.
- **Lifting magnets and grabs,** which on their own can take up a large share of the rated capacity.

A crane rated at 10 t working with a 0.8 t lifting beam can therefore lift no more than 9.2 t of product. The overload protection, mandatory from 1,000 kg rated load under the Machinery Directive (Annex I, 4.2.2), responds to the total load on the hook and cannot tell product from accessories. For a permanently fitted magnet or grab, have the offer and the operating manual state whether the rated capacity includes the device.

## How many tonnes do you need?

Capacity selection starts with data, not with a round number:

1. **Identify the heaviest single lift.** Use weighed values where you can; drawing weights can omit welds, coatings, fixtures or contents. Include occasional lifts: during maintenance, the heaviest part of a press, a motor or a gearbox can outweigh everything in daily production.
2. **Add every lifting accessory** that will hang between the hook and that load.
3. **Add realistic growth,** based on products, machines or orders actually planned over the crane's service life, not on a general feeling.
4. **Round up to a standard step.** Series hoists typically come in capacity steps such as 3.2, 5, 6.3, 8, 10, 12.5, 16 and 20 t.

Rounding up further ‘just to be safe’ is not free: every extra tonne means a larger hoist, heavier girders, higher wheel loads and bigger test loads. A margin backed by a plan is sensible; a jump from 10 t to 20 t without one can push both the crane and the building into a heavier class.

If heavier loads are likely but not yet certain, there is a middle way: in a new hall, design the runway, columns and foundations for the future capacity now. Strengthening a finished building later is usually far more disruptive.

## Overhead crane capacities from 1 t to 100 t

The ranges below are for orientation only. Span, hook height and duty class decide where a crane falls: a long-span 10 t crane in three-shift operation can be a heavier machine than a 20 t crane serving a short workshop bay a few times a week.

| Range | Typical design | What to check |
| --- | --- | --- |
| ≈ 1–5 t | Single girder; chain or wire rope hoist; workshops, assembly | Can the existing hall carry it? Hook height |
| ≈ 5–20 t | Single or double girder, depending on span, hook height and duty | Span, hook height, duty class |
| ≈ 20–50 t | Mostly double girder with wire rope hoist or crab | Wheel loads, runway, headroom |
| ≈ 50–100 t | Double girder with crab, often main and auxiliary hoist | Runway and building design, erection, test loads |

Chain hoists are common at the lower end of the light range; wire rope hoists take over as capacity, lifting height and duty grow. In the medium range, a 10 ton overhead crane is often built with a single girder, while long spans, maximum hook height or intensive duty favour two girders.

From around 20 t, double girder designs dominate: a 20 ton bridge crane typically carries a wire rope hoist on a double-rail trolley or an open-winch crab. Heavy cranes often add an auxiliary hoist – written as 50/10 t, for example – that handles light loads faster and helps turn loads; the two capacities do not add up. In the very heavy range, wheel loads can grow so high that the end carriages need bogies with eight wheels instead of four, and crane, runway and building must be designed together.

## What grows with capacity

Capacity scales the whole crane. As it rises, so do the following:

- **Girders and crane weight.** To stay within stress and deflection limits, girders get deeper and heavier, and end carriages and wheels grow. This extra dead weight appears in every wheel load and in every transport and erection plan.
- **Wheel loads.** They peak when the loaded trolley stands at the end of its travel next to one rail, and they size the rail, runway beams, columns and foundations. Our guide to [crane runway requirements](https://ervancranes.com/en/blog/crane-runway-requirements/) shows how these loads reach the building.
- **Hoist and hook height.** Higher capacities need more rope falls or a heavier rope, a bigger drum and a bigger hook block. On the same hoist, 4/1 reeving instead of 2/1 doubles the capacity but halves the hoisting speed and the lifting height. At a given rail level, a larger hoist can also cost hook height.
- **Speed and power.** Hoisting power is proportional to load × speed, so twice the capacity at the same speed needs roughly twice the power. Heavy cranes therefore usually lift more slowly, and a fine creep speed for setting loads down matters more.
- **Test loads.** Commissioning includes a static test with at least 1.25 × the rated load and a dynamic test with 1.1 × (Machinery Directive, Annex I, 4.1.2.3): at least 12.5 t of verified test weights for a 10 t crane, 62.5 t for a 50 t crane. Plan who supplies them and how they reach the hall – see [overhead crane installation and commissioning](https://ervancranes.com/en/blog/overhead-crane-installation-and-commissioning/).
- **Cost.** The price rises with capacity, and not only at the crane: runway, building, erection equipment and test logistics grow with it.

## Capacity and duty class belong together

Capacity tells you how much a crane may lift; the duty class tells you how often and how close to that limit it works. A 10 t crane feeding a three-shift production line with near-capacity lifts every few minutes may need larger hoist and travel mechanisms than a 16 t crane in a maintenance bay that lifts a few times a week – and its structure has to be verified for far more load cycles.

The reason is fatigue and wear: a mechanism's life is used up in proportion to its running time and roughly with the third power of the load, the assumption behind duty classification. Hoist catalogues therefore rate the same frame size at a lower capacity in a higher mechanism group; [crane duty classification under FEM, ISO and CMAA](https://ervancranes.com/en/blog/crane-duty-classification-fem-iso-cmaa/) explains how the groups are set. In practice, specify capacity and duty class together, for the structure and each mechanism, and never compare offers by tonnage alone.

## Raising capacity later: a modification, not a setting

Resetting the overload protection does not raise a crane's capacity. A heavier load acts on every link in the load path – girders and welds, end carriages and wheels, rope, drum, gearbox, brake, motors and travel drives – and, through higher wheel loads, on the runway and the building.

A capacity increase therefore starts with an engineering verification of that entire path. It usually means a new hoist or trolley, sometimes structural strengthening, followed by load tests at the new capacity, a new rating plate, updated documents and an inspection before reuse. Because it changes the crane's performance, it may also be a substantial modification, after which the crane must be assessed like a new machine; Regulation (EU) 2023/1230, applicable from 20 January 2027, defines the term explicitly. Our article on [overhead crane modernization](https://ervancranes.com/en/blog/overhead-crane-modernization/) walks through the process.

Upgrades are most realistic where the original design already holds reserves – one more reason to put planned growth into the first specification.

## How Ervan Cranes approaches capacity

Ervan Cranes manufactures [single and double girder overhead cranes](https://ervancranes.com/en/products/overhead-cranes/) from 1 to 100 t at its facility in Torbalı, İzmir. Each crane is engineered to its load, span, lifting height and duty class; other figures are determined per project. Capacity is settled in the needs analysis and fixed in the technical design, and the team that designs the crane also installs, load-tests and commissions it. For existing cranes, our modernization service covers hoist, control and drive renewal as well as capacity and safety improvements.

## Frequently Asked Questions

### Can a 10 ton overhead crane have a single girder?

Yes, single girder cranes are common at 10 t. Span, required hook height and duty class decide: on long spans the girder becomes very deep and heavy, and where every centimetre of hook height counts or the crane works intensively, a double girder design is often the better choice.

### Is a higher capacity automatically safer?

No. A larger crane is heavier and more expensive, but not automatically safer. Its overload protection guards the crane, not your slings or the lifting points on the load – a 20 t crane will lift 12 t on a 10 t sling without complaint. Safety comes from the right capacity and duty class, suitable accessories and trained operators.

### Do slings and lifting beams count towards the capacity?

Yes. Everything between the hook and the load counts, from shackles to magnets; only the hook block and rope belong to the crane itself. Each accessory must also be rated for the load in the way it is used – a multi-leg sling's working load limit, for example, falls as the angle of its legs increases.

### Can two cranes lift a heavier load together?

Only as a planned tandem lift. The load must be shared so that neither crane exceeds its own rated capacity, even if the load tilts or the motions run out of step, and a competent person should prepare a lift plan. Where long loads are routine, two hoists on one crane or a tandem control that synchronizes both cranes is the better set-up.

Send us your heaviest load, the weight of the lifting accessories, the span, the hook height you need and how often the crane will work – we will turn these figures into a capacity and duty class that fit your building. Share them through our [quote request form](https://ervancranes.com/en/request-a-quote/).

[Get a Quote](https://ervancranes.com/en/request-a-quote/) [All articles](https://ervancranes.com/en/blog/)

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