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Handcraft

Pattern Scaling Tool

Scale a leather pattern up or down and see what happens to the area, the leather you need and the cost.

Leather Craft
Scaling a pattern is not the same as scaling the measurements on it. Double the width of a bag and you double the leather; double the width and the height and you quadruple it. This tool scales a pattern by a percentage in one or both directions and reports the new dimensions, the new area, the leather to buy and the cost, so a size change does not turn into a material surprise halfway through cutting.

At a glance

What you enter
Original pattern width, Original pattern height, Scale, What is being scaled, Seam allowance in the original, Leather the original pattern needs, Leather cost, Leather thickness
What you get
New pattern width, New pattern height, Area factor, Leather the scaled pattern needs, Extra leather, Extra leather as a share of the original, Leather cost of the original, Leather cost of the scaled pattern, Extra leather cost, Seam allowance after scaling, Increase in the largest span, Structure may need stiffening, Smallest dimension is workable, Scale is within a sensible range, Check the hardware sizes, Scaled items per square foot
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 ↓ Read the FAQ ↓ Share this calculator ↓

The width of the finished piece or the pattern piece, whichever you are scaling.

A hundred percent leaves the pattern unchanged. The area changes with the square of this figure.

What is being scaled

Used to check what the seam allowance becomes after scaling, which is usually not what a maker wants.

The area one original item consumes, including its cutting allowance.

Cost per square foot, for the cost comparison.

Thickness does not scale with the pattern. Used to check the stiffness change.

Reset

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

How to use the Pattern Scaling Tool

  1. 1 Enter Original pattern width (mm), The width of the finished piece or the pattern piece, whichever you are scaling.
  2. 2 Enter Original pattern height (mm)
  3. 3 Enter Scale (%), A hundred percent leaves the pattern unchanged. The area changes with the square of this figure.
  4. 4 Enter What is being scaled
  5. 5 Enter Seam allowance in the original (mm), Used to check what the seam allowance becomes after scaling, which is usually not what a maker wants.
  6. 6 Enter Leather the original pattern needs (sq ft), The area one original item consumes, including its cutting allowance.
  7. 7 Enter Leather cost, Cost per square foot, for the cost comparison.
  8. 8 Enter Leather thickness (mm), Thickness does not scale with the pattern. Used to check the stiffness change.
  9. 9 Press Calculate. You get New pattern width, New pattern height, Area factor, Leather the scaled pattern needs, Extra leather, Extra leather as a share of the original, Leather cost of the original, Leather cost of the scaled pattern, Extra leather cost, Seam allowance after scaling, Increase in the largest span, Structure may need stiffening, Smallest dimension is workable, Scale is within a sensible range, Check the hardware sizes, Scaled items per square foot, and every intermediate step stays visible under "How is this calculated?"
  10. 10 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.

A bag scaled to 120 percent

A 200 by 150 millimetre pattern scaled up in both directions.

You enter

Original pattern width
200 mm
Original pattern height
150 mm
Scale
120%
What is being scaled
1
Seam allowance in the original
5 mm
Leather the original pattern needs
2 sq ft
Leather cost
$7.50
Leather thickness
1.60 mm

You get

New pattern width
240.00 mm
New pattern height
180.00 mm
Area factor
1.44
Leather the scaled pattern needs
2.88 sq ft
Extra leather
0.88 sq ft
Extra leather as a share of the original
44.0%
Leather cost of the original
$15.00
Leather cost of the scaled pattern
$21.60
Extra leather cost
$6.60
Seam allowance after scaling
6.00 mm
Increase in the largest span
1.20
Structure may need stiffening
0
Smallest dimension is workable
1
Scale is within a sensible range
1
Check the hardware sizes
1
Scaled items per square foot
0.35

A 20 percent size increase needs 44 percent more leather, so 2.88 square feet instead of 2, and the seam allowance creeps to 6 millimetres.

Open this example in the calculator →

A wallet made wider only

A 110 by 95 millimetre wallet scaled to 130 percent in width and unchanged in height.

You enter

Original pattern width
110 mm
Original pattern height
95 mm
Scale
130%
What is being scaled
2
Seam allowance in the original
4 mm
Leather the original pattern needs
1.10 sq ft
Leather cost
$8.00
Leather thickness
1.20 mm

You get

New pattern width
143.00 mm
New pattern height
95.00 mm
Area factor
1.30
Leather the scaled pattern needs
1.43 sq ft
Extra leather
0.33 sq ft
Extra leather as a share of the original
30.0%
Leather cost of the original
$8.80
Leather cost of the scaled pattern
$11.44
Extra leather cost
$2.64
Seam allowance after scaling
5.20 mm
Increase in the largest span
1.30
Structure may need stiffening
1
Smallest dimension is workable
1
Scale is within a sensible range
1
Check the hardware sizes
1
Scaled items per square foot
0.70

Scaling one direction only is linear: 30 percent wider needs 30 percent more leather, so 1.43 square feet.

Open this example in the calculator →

A pattern scaled down to a card holder

A 200 by 150 millimetre pouch scaled to 60 percent.

You enter

Original pattern width
200 mm
Original pattern height
150 mm
Scale
60%
What is being scaled
1
Seam allowance in the original
5 mm
Leather the original pattern needs
2 sq ft
Leather cost
$7.50
Leather thickness
1.60 mm

You get

New pattern width
120.00 mm
New pattern height
90.00 mm
Area factor
0.36
Leather the scaled pattern needs
0.72 sq ft
Extra leather
-1.28 sq ft
Extra leather as a share of the original
-64.0%
Leather cost of the original
$15.00
Leather cost of the scaled pattern
$5.40
Extra leather cost
$-9.60
Seam allowance after scaling
3.00 mm
Increase in the largest span
0.60
Structure may need stiffening
0
Smallest dimension is workable
1
Scale is within a sensible range
1
Check the hardware sizes
1
Scaled items per square foot
1.39

At 60 percent the smallest dimension is 90 millimetres, which is still workable, and the leather falls to 0.72 square feet.

Open this example in the calculator →

Guides that go with it

How to Convert Craft Measurements from Inches to Centimeters

If you have ever followed a pattern in inches and then bought fabric or yarn labelled in centimetres, you already know the small panic that sets in. This guide walks you through converting craft measu...

Inches vs Centimeters: The Ultimate Handcraft Conversion Guide

You found a pattern you love. The measurements are in inches. Your ruler is in centimeters. Or the reverse: a European yarn chart in centimeters, a US hook set labeled in millimeters and inches. Sudde...

The Complete Handcraft Measurement Guide for Beginners

If you are new to crafting, measuring is usually the first place things go sideways: a cut is 3 mm short, two "identical" squares are not identical, or a pattern that looked fine on paper does not fit...

Frequently asked questions

Does doubling a pattern double the leather?
No, it quadruples it if you double both dimensions. The area of a shape scales with the square of the linear scale, so a pattern at 200 percent uses four times the leather. Widening a bag without changing its height, on the other hand, is linear: 150 percent wider uses 150 percent of the leather. This is the single most common surprise in scaling a leather pattern.
Should the seam allowance be scaled with the pattern?
Usually not. A 5 millimetre seam allowance is a working allowance set by the thickness of the leather and the size of the stitch, not by the size of the item. Scaling a pattern to 150 percent carries the allowance to 7.5 millimetres, which is wrong for the leather you are using. Scale the design line, then add the same seam allowance you would use at any size.
Why does my scaled up pattern sag?
Because the leather thickness did not scale with it. Bending stiffness rises with the cube of the thickness, while the unsupported spans rise only linearly with the pattern, so a larger version of the same design is proportionally much flatter. Add a stiffener, use a thicker leather, or add a seam or a gusset that shortens the longest unsupported span. Scaling up is not only a matter of larger pieces.
Can I scale a pattern down to make a small version?
Down to about 70 percent, yes. Below about 60 percent the small pieces become awkward to cut and skive, the seam allowance takes up a larger share of each piece, and the hardware no longer has anywhere to sit. Below half size, redraw the design at the size you want rather than scaling, because a scaled down pattern is rarely well proportioned even when it technically fits together.
What does not scale with a pattern?
Hardware, leather thickness, the seam allowance and the stitch spacing. A buckle, a snap, a rivet, a D ring and a zip all come in fixed sizes, so any part of the pattern that engages them has to be adjusted to the hardware rather than scaled. Stitch spacing stays at the same millimetres, which means a larger item simply has more stitches in it, and a scaled item takes proportionally longer to sew than the scale suggests.

More money questions answered →

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