About
Skirt Calculator turns the geometry of skirt drafting into clear, reliable calculations. Enter your body measurements once to get exact cutting numbers, plus a pattern you can print at true scale on a home printer.
What it is
Five focused tools for circle, half circle, pleated and tiered skirts and bias binding. Everything runs locally in your browser — read our privacy policy.
The cut waist radius automatically subtracts your seam allowance, so your stitched waist matches your measurement.
Visual cutting layouts nest panels on 45"/60" (115/150 cm) fabric to show exactly how much to buy.
Tiled A4 and Letter PDFs include test squares, alignment marks, and a handy one-page cheat sheet.
Switch between units at any time; your values convert automatically.
Why we built it
Every skirt type divides the waist by a different number — 2π, 1.5π, π or π/2 — and the hem, layout and yardage all build on that one radius. A slip in the first step carries through to the fabric you buy.
The calculator does each step the same way every time and shows the numbers it used.
Many patterns cut the waist on the stitching line. Sew a 5/8" seam on top of that and a full circle waist grows by about 3.9" — enough for the skirt to slide off your hips.
Here the cut waist radius always subtracts the seam allowance: 4.456 − 0.625 = 3.831" for a 28" waist.
Accuracy
No reviews or testimonials — just checks you can repeat yourself.
Automated tests run the same code as the calculators against hand-worked values — for example a 28" waist must give a 4.456" full-circle radius and a 27.456" cut hem radius for a 22" skirt.
Every pattern page carries a 2" and a 5 cm calibration square. The tests check that both are exactly to size in the PDF, so you can verify your printer before you tape a single page.
Every radius comes from the standard drafting formula r = L ÷ (2π × k) — the same one in the circle skirt math guide, with every step shown.
Worked examples
Two skirts straight from the calculator. Open either one to check the numbers yourself.
Worked example
Result
Worked example
Result
Pleats too: a 28" waist with 1 1/2" knife pleats gives 19 pleats and 85 1⁄4" of flat fabric — open it in the pleat calculator.
The tools
Enter your waist and length — get the radius, yardage and a 1:1 PDF pattern in seconds.
