Did You Get The Right Bolt Size For Your Sofa Leg?

Finding the right bolt size for your sofa or lounge legs can be challenging, particularly if you're planning to replace or swap them out! In this guide, we will walk you through the most common sizes and give you some handy tips to help you identify the bolt size you need.

Here are the common bolt sizes:

 

5/16" Bolts

 

• Diameter: 5/16 inches (7.94 mm)
  These are the most common bolt size you’ll find on sofa legs, especially for sofas imported into the Australian market. You might be wondering why an imperial size is so prevalent. It’s because most sofas are manufactured to meet the standards of the American market, where 5/16" is the go-to size!

 

M8 Bolts

 

• Diameter: 8 mm
  These are often used in European-made sofas and are a staple in many IKEA designs. That said, not all IKEA sofas use M8 bolts, as they sometimes use different methods to attach the legs. But if your sofa leg has a central bolt, chances are it’s an M8. Easy to identify, right?

 

3/8" Bolts

 

• Diameter: 3/8 inches (9.53 mm)
  These are a heavier-duty option and are typically found on larger, more robust sofas, often imported from overseas or those that are made-to-order or those that use solid wood.

 

M10 Bolts

 

• Diameter: 10 mm
  Think of these as the heavy-duty version of the M8 bolt. They’re commonly used on European-made sofas that need a bit more strength.

 

How to Identify Your Bolt Size:

The simplest way to figure out your bolt size is to measure the diameter of the bolt. Make sure you’re measuring the entire thread from one side to the other.

• Metric bolts (like M8 or M10) will be exactly 8 mm or 10 mm in diameter.
• Imperial bolts (like 5/16" or 3/8") will be slightly smaller—7.94 mm and 9.53 mm, respectively. If you’ve got a pair of callipers handy, they can make this measurement easy!

One thing to keep in mind: while M8 and 5/16” bolts are close in size, they’re not interchangeable. They have different thread pitches (the angle of the threads), so if you try to force one into the other, it might seem to work at first but will eventually lock up after a few turns. If you’re unsure, you can test the thread by using an M8 or 5/16” nut. Many hardware stores, like Bunnings, also have thread-size testing boards to help you figure it out.

 

Here at Urban Hardware, we work with a variety of suppliers; some only use 5/16” bolts, while others offer customisation options to match your sofa’s specific bolt size. Take a look through our range to find a leg that suits your needs.

If you’ve fallen in love with a leg that doesn’t match your sofa’s bolt size, don’t stress! We have mounting plates, T-nuts, and inserts that can help you adapt the leg to your sofa.

 

We hope this guide has made the process a little less daunting and helps you find the perfect legs for your sofa. Happy shopping!