Circle Skirt Calculator — Free & Easy
Draft accurate waist seamline radius, inner cutting radius, outer radius and finished hem arc for full, three-quarter, half or quarter circle skirts.
Loading the interactive calculator. Enable JavaScript to enter your values, or use the formulas and worked example below.
How to use the Circle Skirt Calculator
Draft accurate waist seamline radius, inner cutting radius, outer radius and finished hem arc for full, three-quarter, half or quarter circle skirts.
- Step 1. Measure the waist at the finished seamline, then add any wearing ease.
- Step 2. Choose full, three-quarter, half or quarter circle fullness.
- Step 3. Enter finished skirt length and both seam and hem allowances.
- Step 4. Use the calculated cutting radii from the same circle center; check fabric width and panel placement separately.
Important: Outputs are pattern geometry, not guaranteed optimized fabric-yardage or fitting recommendations.
Circle Skirt Calculator formula explained
Waist seamline radius = (waist + ease) ÷ (2π × fraction of circle). Inner cutting radius = waist seamline radius − waist seam allowance. Outer cutting radius = waist seamline radius + skirt length + hem allowance.
All calculator outputs depend on the measurements, units and assumptions you enter. Intermediate calculations use unrounded numeric values; formatted results may be rounded for easier reading. For any consequential purchasing or construction decision, verify supplier specifications and regulations.
Worked example with real numbers
A 28-inch waist plus 0.5 inches ease in a full-circle skirt has a waist radius of 28.5 ÷ 2π ≈ 4.54 inches. With 0.5-inch waist seam allowance, the inner cut radius is about 4.04 inches.
The example illustrates the formula independently of the interactive fields. You can change the values above to match your own project and compare results.
Frequently asked questions
Why subtract seam allowance from the inner radius?
The waist stitching line sits farther from the circle center than the inner raw edge. Subtracting the allowance keeps the finished waistline size.
Can a full skirt always be cut in one piece?
No. If the required flat pattern width exceeds usable fabric width, multiple panels and extra seam allowances are necessary.
Can I use a pull-on elastic waist?
Only if the opening or fabric stretch lets it pass over the hips; a fitted woven skirt may need a zipper or another closure.
Will the skirt hang at exactly the calculated length?
Fabric on the bias may grow when hanging, so allow the garment to relax before leveling and hemming.