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What Size Crane Do I Need? A Complete Capacity Guide

Author:
Granada Cranes
SWF Slewing Free Standing Jib Crane Vecto

One of the first questions when specifying an overhead crane is “what size do I need?” Getting the capacity right is crucial – too small and you can’t lift what you need to, too large and you’ve overspent on a crane that’s more than the job requires. This guide helps you work out the right capacity for your application.

Understanding Crane Capacity

Crane capacity – also called Safe Working Load (SWL) or Working Load Limit (WLL) – is the maximum weight the crane is designed to lift safely. This is the total weight suspended from the hook, which includes:

  • The load itself – the item you’re lifting
  • Lifting accessories – chains, slings, shackles, spreader beams, grabs, magnets
  • The hook block – usually accounted for in the crane’s rated capacity

Critical: Don’t Forget Lifting Accessories

A common mistake is to specify crane capacity based only on the load weight. If your heaviest load is 4.5 tonnes but you use a 500kg spreader beam, you need at least 5 tonnes capacity. Always factor in the weight of lifting accessories.

How to Calculate the Capacity You Need

Simple Capacity Formula

Work out your minimum crane capacity using this formula:

Maximum Load Weight + Lifting Accessories + Safety Margin = Required Capacity
  • Maximum load – the heaviest single item you’ll ever need to lift
  • Lifting accessories – total weight of slings, beams, grabs, magnets etc.
  • Safety margin – typically 10-20% for future needs and variations

Example Calculation

A steel fabricator needs to lift steel plate packages:

  • Heaviest plate package: 3,800kg
  • Lifting magnet: 450kg
  • Chains and shackles: 50kg
  • Total lifted weight: 4,300kg
  • With 15% margin: 4,945kg
  • Recommended capacity: 5 tonnes

Crane Capacities at a Glance

Here’s a quick reference showing typical applications for each capacity range:

Capacity Typical Applications Common Industries
1-3 Tonnes Small components, tooling, maintenance tasks, light assembly Workshops, maintenance bays, light manufacturing
4-6 Tonnes Engine blocks, machine parts, steel sections, palletised goods Engineering, fabrication, warehousing
10 Tonnes Heavy machinery, large fabrications, steel plate, vehicle components Heavy engineering, automotive, steel processing
15 Tonnes Large steel assemblies, heavy equipment, press tools Steel fabrication, heavy manufacturing
20 Tonnes Steel coils, large castings, heavy plant equipment Steel stockholding, foundries, power generation
30+ Tonnes Very heavy fabrications, ship sections, large transformers Shipbuilding, heavy industry, infrastructure

Browse Cranes by Capacity

Explore our overhead crane range by tonnage:

1-3 TonLight Duty
4 Ton4,000kg
5 Ton5,000kg
6 Ton6,000kg
10 Ton10,000kg
15 Ton15,000kg
20 Ton20,000kg
30+ TonHeavy Duty

Capacity Guide by Application

Not sure where to start? Here are detailed breakdowns for each capacity range:

1-3 Tonne Cranes

1,000-3,000kg

Ideal for light manufacturing, maintenance, and assembly operations where loads are relatively small but need to be moved frequently.

  • Small machine components
  • Tooling and fixtures
  • Maintenance lifting
  • Assembly line work
  • Packaging and pallets

View 1-3 Ton Cranes →

4 Tonne Cranes

4,000kg

A popular choice for general engineering workshops where loads exceed light-duty requirements but don’t need heavy-duty equipment.

  • Small engine blocks
  • Steel beams and sections
  • Medium fabrications
  • Machine tool loading
  • Container handling

View 4 Ton Cranes →

5 Tonne Cranes

5,000kg

One of the most common capacities, offering a good balance between capability and cost for general industrial applications.

  • Automotive components
  • Steel plate handling
  • General fabrication
  • Warehouse operations
  • Machine shop work

View 5 Ton Cranes →

6 Tonne Cranes

6,000kg

Slightly more capacity than 5 tonne for applications where standard loads occasionally exceed 5 tonnes with lifting accessories.

  • Heavier fabrications
  • Large vehicle components
  • Press tool handling
  • Steel processing
  • Die and mould work

View 6 Ton Cranes →

10 Tonne Cranes

10,000kg

The workhorse of heavy engineering. Capable of handling substantial loads while still being suitable for single girder designs.

  • Large steel fabrications
  • Heavy machinery
  • Steel stockholding
  • Automotive production
  • Aerospace components

View 10 Ton Cranes →

15 Tonne Cranes

15,000kg

For heavy industrial applications requiring substantial lifting power. Often the threshold where double girder designs become preferred.

  • Heavy steel assemblies
  • Large machine tools
  • Transformer handling
  • Heavy press work
  • Infrastructure components

View 15 Ton Cranes →

20 Tonne Cranes

20,000kg

Heavy duty lifting for demanding industrial environments. Typically requires double girder construction for the load and span.

  • Steel coils
  • Large castings and forgings
  • Power generation equipment
  • Shipbuilding components
  • Mining equipment

View 20 Ton Cranes →

30+ Tonne Cranes

30,000kg+

Specialist heavy lifting for the most demanding applications. Custom-engineered double girder cranes up to 60+ tonnes capacity.

  • Very heavy fabrications
  • Ship sections
  • Large transformers
  • Steelworks applications
  • Heavy plant and machinery

View 30+ Ton Cranes →

Quick Decision Guide

What Capacity Do You Need?

Heaviest load under 3t
Consider a 1-3 tonne crane – cost-effective for light duty applications

Heaviest load 3-5t
A 5 tonne crane gives you capacity plus headroom for accessories

Heaviest load 5-8t
Look at 10 tonne cranes – still achievable with single girder design

Heaviest load 8-12t
15 tonne capacity – may require double girder depending on span

Heaviest load 12-18t
20 tonne double girder crane recommended

Heaviest load over 20t
30+ tonne heavy duty crane – custom engineered to your requirements

Industry-Specific Capacity Examples

Industry Typical Loads Common Capacities
Steel Fabrication Steel plate, beams, finished fabrications 5t, 10t, 15t
Automotive Body panels, engines, sub-assemblies 3t, 5t, 10t
Aerospace Aircraft components, tooling, engines 5t, 10t, 15t
Warehousing Palletised goods, machinery, stock 3t, 5t
Steel Stockholding Steel coils, plate packs, sections 10t, 15t, 20t
Shipbuilding Hull sections, heavy equipment 20t, 30t, 50t+
Machine Shops Workpieces, tooling, finished parts 3t, 5t
Power Generation Turbines, generators, transformers 15t, 20t, 30t+

Things to Consider Beyond Capacity

While capacity is crucial, it’s not the only factor. These also influence your crane specification:

Higher Capacity Affects

What changes as capacity increases
  • Crane weight – heavier cranes need stronger building structures
  • Girder type – higher capacities often require double girder
  • Hoist size – larger hoists need more headroom
  • Cost – both initial purchase and running costs increase
  • Power requirements – bigger motors need more electrical supply

Future-Proofing

Planning for tomorrow’s needs
  • Will your lifting requirements increase?
  • Are you planning to take on heavier work?
  • Could you acquire heavier equipment?
  • Is there potential for business growth?
  • What’s the cost difference to go one size up?

The Upgrade Question

It’s much cheaper to specify slightly higher capacity from the start than to upgrade later. If you’re between sizes and there’s any chance you’ll need the extra capacity, consider going up. The price difference is often modest compared to the cost of replacing or modifying a crane later.

What Information Do You Need to Get a Quote?

Information to Gather

  • Maximum single load weight you need to lift
  • Weight of lifting accessories (slings, beams, grabs, magnets)
  • Typical everyday load weight
  • How often the crane will be used (lifts per hour/day)
  • Building dimensions (width, length, height to underside of roof)
  • Any specific requirements (explosion-proof, clean room, outdoor use)

Common Mistakes When Choosing Capacity

  • Forgetting lifting accessories – slings, spreader beams and grabs can add hundreds of kilos
  • Using average weight, not maximum – the crane must handle your heaviest load, not your typical load
  • No safety margin – allow 10-20% for future needs and load variations
  • Ignoring future plans – if you’re growing, factor in tomorrow’s requirements
  • Over-specifying – paying for capacity you’ll never use wastes money and may need unnecessary building reinforcement

Not Sure What Size You Need?

Our team can help you work out the right capacity for your application. Tell us what you need to lift and we’ll advise on the best solution.

Get Expert Advice

Or call 0800 376 27 27

Summary

Key Takeaways

  • Calculate total lifted weight – load plus all lifting accessories
  • Add a safety margin – 10-20% for future needs and variations
  • Consider future requirements – upgrading later is expensive
  • Match capacity to application – don’t over or under-specify
  • Higher capacity affects more than price – building structure, headroom, power supply
  • Ask for advice – a good supplier will help you get it right

Choosing the right crane capacity is a balance between meeting your current needs, allowing for future growth, and not over-investing in capability you won’t use. Take time to audit your lifting requirements thoroughly before specifying.

Explore our full range of overhead gantry cranes from 1 tonne to 60+ tonnes, or contact our team to discuss your requirements.

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