A sewing pattern size adjustment calculator helps you resize commercial sewing patterns to fit your actual body measurements. Because most patterns are drafted for one specific size, scaling the pattern up or down — or grading between sizes at different measurement points — ensures a better fit without starting from scratch.
Pattern Size Adjustment
Compare your measurements to the pattern size for scaling percentages
From size chart, not finished measurement
Seam Adjustment Guidance
How to Use the Sewing Pattern Size Adjustment Calculator
Sewing patterns are drafted for a specific set of body measurements, but few people fit those measurements exactly. The sewing pattern size adjustment calculator shows you the scaling percentage between your measurements and the pattern's measurements, and gives concrete guidance on where to add or remove ease at bust, waist, and hip seams.
Step 1: Take accurate body measurements
Measure bust, waist, and hips at their fullest points while wearing the undergarments you plan to wear under the finished garment. Stand naturally — don't breathe in or suck in. For the bust, measure around the fullest part, keeping the tape parallel to the floor. For hips, measure around the fullest part of your seat, usually 7–9 inches below the natural waist.
Step 2: Find the pattern's body measurements
Commercial patterns include a size chart with body measurements (not finished garment measurements). These are the numbers to compare against yours. For example, if the size 14 chart shows a 36-inch bust, enter 36 in the Pattern Bust field — not the finished garment's bust measurement, which includes ease built in by the designer.
Step 3: Read the scaling percentages
Each percentage shows how much larger or smaller your measurement is compared to the pattern. A bust scaling of 111% means your bust is 11% larger — you need to add width at the side bust seams. Ideally all three percentages are close to each other. If they differ significantly (e.g., 108% bust but 116% hips), the garment needs to be graded between sizes — adding at the hips more than the bust to match your proportions.
Step 4: Apply adjustments to your pattern
For small differences (under 10%), adjust at the side seams. For larger differences, use full-bust adjustments (FBA), sway-back adjustments, or other standard alterations. The calculator suggests how many inches to add or remove at each seam. Remember to adjust front and back pattern pieces by the same total amount, split across two side seams.
Frequently Asked Questions
Is this sewing pattern size adjustment calculator free?
Yes, completely free with no signup required. Enter your measurements and get instant scaling calculations.
Is my data safe and private?
Yes. All calculations run locally in your browser. No data is sent to any server or stored.
How do I resize a sewing pattern for a different size?
To resize a sewing pattern, calculate the ratio between your measurement and the pattern's measurement for each body section (bust, waist, hips). For example, if the pattern's bust is 36 inches but yours is 40 inches, the scaling factor is 40/36 = 1.11 — you need 11% more ease in the bust. Grade the side seams proportionally between your three key measurements.
What is pattern grading?
Pattern grading is the process of scaling a pattern from one size to another. Professional grading adds or subtracts a set amount at each seam point rather than scaling the whole pattern uniformly. This calculator provides basic scaling guidance — for complex multi-size grading, consider grading rulers or professional grading software.
Should I adjust the pattern to my exact measurements?
You typically add ease to your body measurements before comparing to the pattern. Ease is extra room for movement and comfort. Woven garments need 2–4 inches of ease in the bust; knit fabrics need less due to stretch. Always compare your measurements + desired ease to the pattern's finished measurements, not just the pattern's size chart body measurements.
Can I print a scaled pattern at home?
Yes. Most home printers allow you to print at a specific percentage (e.g., 108%). Use the scaling percentage from this calculator when printing. Print a 1-inch test square from the pattern PDF first to verify your printer's scale is accurate before printing full pages.