What’s the difference between a wrench and a spanner?

Wrenches and spanners are ultimately designed to do the same job – tightening or loosening nuts and bolts. While this can sometimes lead to confusion between them, they’re actually two separate tools with their own characteristics and specific uses.

Defining a wrench

In English, a wrench generally refers to adjustable wrenches, which have a moveable lower jaw to adjust to different size nuts and bolts. They’re great because one tool will cover a wide variety of different size fastenings in both metric and imperial – although there is still a minimum and maximum size to watch out for.

The downside, however, is that wrenches are typically quite bulky tools – especially around the jaws – which makes it difficult to use them in narrow spaces or for precision work, which is especially relevant when thinking about automotive jobs. Because they aren’t size-specific, there’s also arguably more risk of rounding the fastening, which can lead to frustration and cost of replacement.

Defining a spanner

Spanners are size-specific. The most common is the combination spanner, which has a closed – ‘box’ – end and an open end to help with different access points, although there are a wide variety of different types such as double box or offset spanners.

The head is slimmer, meaning that it’s easier to fit into narrower spaces and the size-specific nature lessens the risk of rounding. If you know which size you require, then you’ll get the job done quicker as you don’t have to adjust the tool each time, and there is a certain satisfaction from using the ‘right tool for the job’.

So why the confusion?

Aside from having very similar purposes, there’s the fact that the terminology for these tools is different in UK English and American English. American English speakers use ‘wrench’ as an all-encompassing term for both wrenches and spanners, while UK English speakers distinguish between ‘wrenches’ and ‘spanners’ as described above.

Our recommendation

We’d always recommend using spanners when you’re doing automotive work, as they’re the right tool for the job. However, there are times when adjustable wrenches will get you out of trouble – and that’s why we offer both types of tool in our modular tray sets.