What's the Difference Between WLL and SWL?

When you’re browsing the web for lifting equipment, you will come across the terms ‘working load limit’ and ‘safe working load’ quite frequently. So what exactly do these terms mean—are they just two different names for the same thing, or is there a difference between them? Read on to find out…

The terms working load limit (WLL) and safe working load (SWL) both refer to the maximum weight that a given piece of equipment can safely lift. For example, if a chain hoist has a WLL or SWL of 500kg, it should not be used to lift loads that weigh more than 500kg.

The terms WLL and SWL are often used interchangeably. The Lifting Operations and Lifting Equipment Regulations 1998—better known as LOLER—favour the term ‘safe working load’, stating that…

“All lifting equipment, including accessories, must be clearly marked to indicate their 'safe working loads' (SWL) - the maximum load the equipment can safely lift.”

However, in more recent years, WLL has replaced SWL as the preferred term in most formal usage. For instance, ISO 17096:2015 (an international standard that focuses on load lifting attachments for cranes) uses the term ‘working load limit’, defining this as “the maximum load the attachment is designed to lift under the conditions specified by the manufacturer”.

In most cases, it doesn’t really matter whether you use the term WLL or SWL—both are widely understood to mean ‘the maximum load this product was designed to lift’.

That said, some people do use the two terms to differentiate between the product’s maximum lifting capacity in ideal conditions and the maximum load that can be safely lifted in the present circumstances.

WLL vs SWL

When the terms WLL and SWL are used to refer to two different figures, this is usually what is meant:

• Working load limit (WLL) is the absolute largest possible load the equipment can safely lift in perfect conditions. That means you’re using the product in its optimal configuration and there are no mitigating factors in play that might reduce its lifting capacity.
  
  
• Safe working load (SWL) is the largest load the equipment can safely lift in the conditions you’re actually working with. If you’re using the product in an alternative configuration, or if the environment you’re working in is sub-optimal, the safe working load may be somewhat lower than the maximum working load limit.

In other words, the WLL tells you how much the equipment can lift in theory and the SWL tells you how much the equipment can lift in practice.

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At SafetyLiftinGear, we are committed to providing our customers with top-quality lifting gear alongside all the information required to use the equipment safely. That’s why we always display the working load limit (WLL) on our product pages.

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For more information about our products and their load capacities, please don’t hesitate to get in touch and a member of our team will be happy to help.