When you work at height, “load” can mean two very different things. It might be the weight you’re lifting into position (plant, steelwork, truss, pallets). Or it might be the forces your safety system must withstand if something goes wrong. Either way, the terminology on tags, certificates and product pages matters—because choosing the wrong rating can put people and equipment at risk.
If you’ve already read our guide to the difference between WLL and SWL, this post goes one step wider. (If you haven’t, start here: What’s the Difference Between WLL and SWL?.) Below is a practical load-terminology cheat sheet, plus examples of which jobs each rating is most relevant for.
WLL and SWL: the day-to-day limits
Working Load Limit (WLL) and Safe Working Load (SWL) are the ratings you’ll most often see on lifting and rigging hardware. In plain language, they point to the maximum load the product is intended to handle in service. That’s why searches like “wll meaning”, “swl meaning”, and “safe working load” come up when someone is checking whether equipment is suitable for a lift.
Use WLL/SWL when you’re selecting:
- Hoists and chain blocks for lifting and positioning (e.g., a 1 tonne chain block)
- Shackles and connectors in a lifting system (e.g., a 5 ton D shackle)
- Lifting accessories where the rating changes with configuration (angle of slings, multi-leg assemblies, etc.)
MBL / MBS: the “breaking” number (not the working number)
Minimum Breaking Load (MBL) or Minimum Breaking Strength (MBS) is the load where the product is expected to fail in a test. It is not the number you plan your lift around. Manufacturers apply a safety factor (also called a design factor) to turn that breaking figure into a working rating.
You’ll often see MBS language on load restraint products like heavy duty ratchet straps, where standards may show both an in-service capacity (LC) and a breaking figure.
Proof load: the confidence check
Some lifting gear is proof tested above its working rating to confirm integrity. Proof load is not permission to lift more—it’s simply evidence the product can withstand a higher test load without permanent deformation. It’s most relevant for inspection regimes and documentation.
Where this matters in real work-at-height jobs
Construction & MEP installs: If you’re lifting plant to a roof or positioning steelwork, start with WLL/SWL on the lifting path—hoist, slings, shackles, and connectors.
Entertainment & events: Chain blocks are common for truss and staging. Match the WLL to the total suspended load, including rigging hardware.
Transport & haulage: For tie-downs, check both the LC and the MBS so you’re not overestimating strap performance.
Final warning: lifting ratings ≠ fall protection ratings
Fall arrest equipment isn’t selected by “WLL vs SWL”. It’s certified to different standards and designed to absorb energy during a fall, not lift materials. If your job mixes lifting and working at height, keep systems distinct: use certified lifting gear for loads, and purpose-built fall protection equipment for people.
Need help picking the right kit for the job? Tell us what you’re lifting (or securing), where you’re working, and how it’s being used—then we’ll help you match the right terminology and the right equipment to your site conditions.
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