Circle Skirt Calculator

Choose your circle skirt type

The fuller the skirt, the smaller the waist radius – because more circle has to fit around the same waist.

How to calculate the waist radius

Your waist is the inner edge of a circle (or part of one). A full circle has circumference 2πr, so r = W ÷ 2π. A half circle uses half the circumference, so πr = W and r = W ÷ π. A quarter circle uses a quarter, so r = 2W ÷ π. For a 28 in waist:

Seam allowance: draw the waist line at the radius, then cut about 0.5 in (1.5 cm) inside it so the stitched waist ends up the right size. Many sewists also take 0.5–1 in off the waist measurement for woven fabric because the curved, partly bias waistline stretches; staystitch it straight after cutting.

Pull-on and elastic waists

If the skirt has no zip and must pull over your hips, use your hip measurement (plus a little ease) instead of your waist, then gather it with elastic. Knit fabrics with good stretch can use the waist measurement with a stretchy waistband.

How much fabric do you need?

Work out the outer radius R = waist radius + length + hem. A one-piece full circle needs a square of 2R × 2R and fabric at least 2R wide. In the 28 in waist, 25 in length example, R = 30.5 in, so a one-piece circle needs a 61 in square – wider than most 60 in fabric once selvages are trimmed. Instead, cut two half circles: each needs 61 in of length and 30 in of width, so about 3.4 yards of 45 in or 60 in fabric laid end to end, with two side seams.

Directional prints, napped fabrics such as velvet and matching a pattern across seams can all need extra fabric. The calculator shows the layout it used so you can adjust.

How to make a circle skirt, step by step

1. Measure your waist (or hips for pull-on) and decide the finished length.
2. Calculate the waist radius and outer radius with the calculator.
3. Fold the fabric to match the layout and mark both arcs from the centre point with a tape measure pinned at the corner, or with a string-and-pencil compass.
4. Cut the waist arc (minus seam allowance) and the hem arc. Staystitch the waist straight away.
5. Sew side seams if you have them, insert a zip or prepare the elastic casing, and attach the waistband or facing.
6. Hang the skirt for 24 hours before hemming – the bias sections drop and lengthen – then level the hem and finish with a narrow or rolled hem.

Choosing fabric for a circle skirt

Fabric weight changes the look more than the pattern does. Lightweight fabrics such as rayon challis, crepe and chiffon drape into soft, swishy folds; medium-weight cottons and linen hold a crisper bell shape; heavy fabrics such as wool crepe or scuba can look dramatic but add weight at the waist. Avoid very stiff fabrics for full and double circles unless you want a structured petticoat look, and pre-wash washable fabric before cutting so it does not shrink later.