Enter the measurement the pattern is designed for, your own measurement for the same dimension, and a pattern piece dimension you want to enlarge or reduce. The scale factor is your measurement divided by the pattern's, and copying at that percentage scales the pieces uniformly. Measure the same dimension on the body and the pattern, such as the bust or the waist, and remember to allow ease if the pattern includes it.
First verify the unscaled print. Simplicity's PDF instructions specify actual size (100%) and a one-inch registration mark or calibration box. Resizing changes seam allowances and details as well as the outline; check a known dimension on the resized sheet before cutting.
Fit depends on more than the single measurement entered here.
Scale percentage (photocopier setting) from pattern's original measurement
| Pattern's original measurement | 36 |
|---|---|
| Your measurement | 40 |
| Pattern piece dimension | 8 |
| Scale percentage (photocopier setting) | 111.1% |
| Scaled pattern-piece dimension (inches) | 8.9 |
Common error: Scaling by the wrong measurement. The scale factor should come from the dimension that matters for the fit, and a chest measure applied to a length changes it too.
Pattern Scaling: formula
OpenStax Prealgebra: ratios and proportions · Simplicity: printing and tiling PDF patterns
Pattern Scaling: changing Pattern's original measurement
| Pattern's original measurement | Scale percentage (photocopier setting) | Scaled pattern-piece dimension (inches) |
|---|---|---|
| 29 | 137.9% | 11 |
| 32 | 125.0% | 10 |
| 36 (example) | 111.1% | 8.9 |
| 40 | 100.0% | 8 |
| 43 | 93.0% | 7.4 |
Pattern Scaling: compare input ranges
| Input | Tested from | To | Scale percentage (photocopier setting): low input | Scale percentage (photocopier setting): high input | Swing |
|---|---|---|---|---|---|
| Pattern's original measurement | 32 | 40 | 125.0% | 100.0% | 25.0% (23%) |
| Your measurement | 36 | 44 | 100.0% | 122.2% | 22.2% (20%) |
| Pattern piece dimension | 7 | 9 | 111.1% | 111.1% | 0.000% |
Pattern Scaling: individual input comparisons
| Input | Value | Scale percentage (photocopier setting) | Scaled pattern-piece dimension (inches) |
|---|---|---|---|
| Pattern's original measurement | 29 | 137.9% | 11 |
| 32 | 125.0% | 10 | |
| 36 | 111.1% | 8.9 | |
| 40 | 100.0% | 8 | |
| 43 | 93.0% | 7.4 | |
| Your measurement | 32 | 88.9% | 7.1 |
| 36 | 100.0% | 8 | |
| 40 | 111.1% | 8.9 | |
| 44 | 122.2% | 9.8 | |
| 48 | 133.3% | 10.7 | |
| Pattern piece dimension | 6 | 111.1% | 6.7 |
| 7 | 111.1% | 7.8 | |
| 8 | 111.1% | 8.9 | |
| 9 | 111.1% | 10 | |
| 10 | 111.1% | 11.1 |
Scale percentage (photocopier setting): Pattern's original measurement against Your measurement
| Pattern's original measurement / Your measurement | 32 | 40 | 48 |
|---|---|---|---|
| 29 | 110.3% | 137.9% | 165.5% |
| 32 | 100.0% | 125.0% | 150.0% |
| 36 | 88.9% | 111.1% | 133.3% |
| 40 | 80.0% | 100.0% | 120.0% |
| 43 | 74.4% | 93.0% | 111.6% |
Pattern Scaling: values and definitions
| Quantity and definition | Value used |
|---|---|
| Pattern's original measurement — The body measurement the pattern is drafted for, in inches. | 36 |
| Your measurement — Your corresponding measurement, in inches. | 40 |
| Pattern piece dimension — The specific pattern-piece dimension you want to scale, in inches. | 8 |
| Scale percentage (photocopier setting) | 111.1% |
| Scaled pattern-piece dimension (inches) | 8.9 |
Pattern's original measurement: half and double
| Pattern's original measurement | Scale percentage (photocopier setting) |
|---|---|
| 18 | 222.2% |
| 36 | 111.1% |
| 72 | 55.6% |
Scaling a pattern is a ratio: your measurement divided by the pattern's. A pattern drafted for a 36 inch measurement, scaled for a 40 inch one, is 111.1 percent, which is the photocopier setting, and an 8 inch piece becomes about 8.9 inches. A single scale factor changes every dimension the same way, so it is good for size but does not fix fit issues such as a longer torso or a wider shoulder.
Scale only when the difference is small. Larger changes need the pattern altered at specific points, not scaled as a whole.
Cut the size on the seam allowance calculator, estimate fabric on the fabric yardage page and adjust quilting on the quilt backing and binding calculator. The percentage and proportion calculators handle the arithmetic, and the ratio simplifier and length converter help with units.
How do I enlarge a pattern by a percentage?
Divide the size you want by the pattern's size and multiply by 100, then copy at that percentage.
Does scaling change the seam allowance?
Yes. Seam allowances scale with the piece, so trim or add to bring them back to the standard width.