Skip to content

Leather Thickness Converter

Convert leather thickness between ounces, millimetres, inches and gauge, and check what the leather suits.

Leather is specified in ounces in the United States, in millimetres almost everywhere else, in fractions of an inch by older harness suppliers, and in gauge by some irons and splitter manuals. This converter moves between all four and, more usefully, says what the thickness is good for: a wallet, a belt, a bag or a sole. It is the tool to check before ordering leather described in a unit you do not work in.

At a glance

What you enter
You have the thickness in, Thickness value, Weight per square foot for an ounce figure
What you get
Thickness in ounces, Thickness in millimetres, Thickness in inches, Thickness in sixtyfourths of an inch, Gauge equivalent, Lower end of the practical range, Upper end of the practical range, Weight band, Suits wallets and small goods, Suits belts and bags, Suits heavy straps and harness, Suits soles, Stiffness against a 1.6 mm leather, Layers to reach four millimetres, Thickness of a three layer seam
Formula shown
Yes, every step, right below your results.
Cost and privacy
Free, no account needed, and nothing you type is stored.

See worked examples โ†“ Read the FAQ โ†“ Share this calculator โ†“

You have the thickness in

The number from the supplier listing or the splitter manual.

Only used to check the ounce rating against a measured thickness. A 4 ounce leather should weigh about 4 ounces per square foot.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Leather Thickness Converter

  1. 1 Enter You have the thickness in
  2. 2 Enter Thickness value, The number from the supplier listing or the splitter manual.
  3. 3 Enter Weight per square foot for an ounce figure (oz), Only used to check the ounce rating against a measured thickness. A 4 ounce leather should weigh about 4 ounces per square foot.
  4. 4 Press Calculate. You get Thickness in ounces, Thickness in millimetres, Thickness in inches, Thickness in sixtyfourths of an inch, Gauge equivalent, Lower end of the practical range, Upper end of the practical range, Weight band, Suits wallets and small goods, Suits belts and bags, Suits heavy straps and harness, Suits soles, Stiffness against a 1.6 mm leather, Layers to reach four millimetres, Thickness of a three layer seam, and every intermediate step stays visible under "How is this calculated?"
  5. 5 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

Four ounce belt leather

A supplier in the United States quoting the belt weight in ounces.

You enter

You have the thickness in
1
Thickness value
4
Weight per square foot for an ounce figure
4 oz

You get

Thickness in ounces
4.00 oz
Thickness in millimetres
1.60 mm
Thickness in inches
0.06 in
Thickness in sixtyfourths of an inch
4.03
Gauge equivalent
16.00
Lower end of the practical range
1.44 mm
Upper end of the practical range
1.76 mm
Weight band
2
Suits wallets and small goods
1
Suits belts and bags
1
Suits heavy straps and harness
0
Suits soles
0
Stiffness against a 1.6 mm leather
1.00
Layers to reach four millimetres
2.50
Thickness of a three layer seam
4.80 mm

About 1.6 millimetres, 0.063 inches, and comfortably in the belt and bag band.

Open this example in the calculator โ†’

A European listing in millimetres

A wallet leather quoted as 1.2 millimetres.

You enter

You have the thickness in
2
Thickness value
1.20
Weight per square foot for an ounce figure
3 oz

You get

Thickness in ounces
3.00 oz
Thickness in millimetres
1.20 mm
Thickness in inches
0.05 in
Thickness in sixtyfourths of an inch
3.02
Gauge equivalent
12.00
Lower end of the practical range
1.08 mm
Upper end of the practical range
1.32 mm
Weight band
2
Suits wallets and small goods
1
Suits belts and bags
0
Suits heavy straps and harness
0
Suits soles
0
Stiffness against a 1.6 mm leather
0.42
Layers to reach four millimetres
3.33
Thickness of a three layer seam
3.60 mm

Three ounces, which is exactly the wallet lining and card slot weight.

Open this example in the calculator โ†’

A harness supplier quoting sixtyfourths

A bridle strap described as 10/64 inch.

You enter

You have the thickness in
3
Thickness value
0.16
Weight per square foot for an ounce figure
10 oz

You get

Thickness in ounces
9.91 oz
Thickness in millimetres
3.96 mm
Thickness in inches
0.16 in
Thickness in sixtyfourths of an inch
9.98
Gauge equivalent
39.62
Lower end of the practical range
3.57 mm
Upper end of the practical range
4.36 mm
Weight band
5
Suits wallets and small goods
0
Suits belts and bags
0
Suits heavy straps and harness
1
Suits soles
1
Stiffness against a 1.6 mm leather
15.19
Layers to reach four millimetres
1.01
Thickness of a three layer seam
11.89 mm

About 3.96 millimetres, or 10 ounces, which is sole and harness weight rather than a belt.

Open this example in the calculator โ†’

Frequently asked questions

How many millimetres is 4 ounce leather?
About 1.6 millimetres. The conversion is one ounce to about 0.4 millimetres, so 2 ounces is about 0.8, 4 ounces about 1.6, 8 ounces about 3.2 and 10 ounces about 4.0. It is an approximation rather than a definition: a dense bridle leather at 4 ounces can measure nearer 1.5 millimetres and a soft garment leather nearer 1.7. Measure if the thickness matters.
What thickness of leather is best for a wallet?
Two to four ounces, which is about 0.8 to 1.6 millimetres. The outer shell of a bifold is usually 3 to 4 ounces so it holds its shape, and the card slots and the interior are 2 to 3 ounces so they stay thin. A wallet made from 5 ounce leather throughout becomes a brick in a pocket, and one made from 2 ounce leather throughout loses its shape within a month.
What thickness is a belt leather?
Four to five ounces, about 1.6 to 2.0 millimetres, is the standard belt weight, and many makers use a two layer construction of two 4 ounce straps laminated together for a 3.2 millimetre belt. A single layer belt at 8 to 10 ounces is heavy and stiff and takes a long time to break in. The stiffness rises with the cube of thickness, so a thicker belt is much stiffer than a proportionally thicker one would suggest.
Why does gauge count backwards?
Because gauge is a wire gauge system, where the number describes the number of drawing operations rather than the size, so a higher number is a thinner material. That is the opposite of the ounce system, where a higher number is a heavier leather. Any time a supplier quotes gauge, convert it to millimetres before comparing it with anything else, and this converter does that conversion for you.
Can I split leather to a thinner thickness myself?
A splitter or a skiving knife can reduce the thickness of a piece, and a hand skiver is the usual tool for thinning an edge where a fold has to sit flat. Splitting a whole hide to a consistent thickness needs a machine splitter, which is a tannery or a leatherworker with the right equipment rather than a bench tool. Practise on scrap, because taking too much off cannot be undone and a split that varies across a strap shows on the finished edge.

More money questions answered โ†’

Share this tool

Send the calculator, or your exact numbers, to whoever needs to see them.

Your browser blocked the clipboard, select the link above and copy it manually.

Embed this calculator on your own site โ†’

We use essential cookies to run this site. Optional partners (advertising and analytics) only load if you accept them. See our Privacy Policy.