Why does this matter?

About Leather Thickness: A Leatherworker’s Guide

No matter if you are making a thin bifold wallet or a thick horse saddle, leather thickness is the single most crucial specification you will deal with. Unfortunately there are three different measurement systems being used throughout the industry — ounces, millimetres and fractions of an inch — which leads to tons of unnecessary confusion. This is especially true if you are new to leatherworking and buying leather from suppliers in different parts of the world.

“Hide suppliers in the United States will sell you leather by the ounce, while those in Europe will sell by the millimetre. It’s crucial to know how to convert back and forth between the two. It’s not just helpful. If you want to order the correct hide the first time, it’s necessary.”

With our free calculator up above, you no longer have to worry about any of it. Enter a value in any one box and the other two update instantly, complete with handy explanations of what that weight is commonly used to make.

Calculator features

How This Tool Can Help You

• ⚡ Convert once and see all three values
  oz ⇔ mm ⇔ inches updated as you type
• 🎯 Select from common leather weights
  Tap presets for 1–12 oz at lightning speed
• 📋 Includes a leather project guide
  Ideal thicknesses for common leather items
• 📱 Designed for phone use
  Made to be used right alongside your tools

About leather weight

How Do We Measure Leather Thickness?

Ounces to millimetres

“Oz” is short for ounces, and it’s the standard measurement of thickness used in the United States. One ounce of leather equals 1/64th inch thick, or about .4 mm. To give you an example: if a piece of leather is catalogued as being 4 oz then it is approximately 1.6 mm thick. This is a common weight for most wallets and card holders.

Help picking sizes

A mistake we see a lot of beginners making is purchasing leather that is too thick or too thin for their intended project. Here’s a rough guide to help you out:

• Thin leather: 1–4 oz (0.4–1.6mm). Great for garments, pouch linings, gloves, watch bands, and anything else that you want to have some degree of flex to it.
• Medium: 4–7 oz (1.6–2.8mm). This is the “sweet spot”. Wallets, belts, small bags and handmade book covers.
• Heavy: 7–12 oz (2.8–4.8mm). Things like belts, holsters, knife sheaths, saddlemaking, or anything that requires some serious structure.

Millimetres and fractions of an inch

Europe uses millimetres because they…well…use the metric system. Australia also commonly uses mm. Japan uses mm as well. If you’re buying leather from an American supplier, they’re going to list the thickness in ounces.

Fractional inches are also widely used by leatherworkers in the US. One eighth of an inch is equal to one ounce of leather. A common fraction you’ll see advertised is 3/16”, which is equal to 2 oz. A half inch is equal to 4 oz. See how easy this is?

Metric, imperial…why can’t we just all use the same system?

Short answer: we hate each other.

Okay, but seriously…

If you’re buying leather from suppliers in different countries, especially when you’re just starting out, knowing how to do this quickly will prevent you from accidentally ordering leather that’s twice as thick as you need. Or ten times. We’ve seen it happen.

FAQ

Questions? We’ve got answers!

How thick is 4 oz leather in mm?

4 oz leather is around 1.6 mm thick (4 times .4 mm). This is one of the most commonly used weights for many types of wallets, card holders, and thinner style purses.

What thickness is 5oz leather?

5 oz leather is about 2 mm thick (5 x .4 mm). This is a popular weight for belts and medium/heavy wallet styles.

Is 4 oz leather good for belts?

Cowhide that is 4 oz (1.6 mm) is quite a bit on the lighter side for belts. The average leatherworker will tell you that 7–9 oz (2.8–3.6 mm) leather is best for most belt styles. That being said, 4 oz leather can work wonderfully for dress belts.

Does 8 oz leather thickness equal 2mm?

Yes, 8 oz equals approximately 3.2 mm. Remember our formula above? 8 multiplied by .4 equals 3.2 mm. Simple!

How accurate is ounce to mm conversion?

The ounce to mm conversion listed above is not perfect. 0.4 mm is an estimate that the leather industry follows. Actual leather thickness will vary from that by 10–15% based on the tannery, where on the hide you’re measuring, and what finishing processes the leather has gone through. If you require a precise thickness for your order, always ask your supplier to send you a sample or spec sheet.

What thickness leather should I use for a wallet?

Between 3–4 oz (1.2–1.6 mm) for the outside, and 1–2 oz (0.4–0.8 mm) for the inside pockets and card slots. Thinner leather helps ensure that your finished wallet isn’t too bulky or thick.