Circle Skirt Calculator
Enter your waist measurement and desired skirt length to get the exact waist radius and total fabric dimensions you need to cut a perfect circle skirt. Choose full, 3/4, half or quarter circle, set your seam and hem allowances, and switch between centimetres and inches. All cutting numbers update instantly as you type.
Formula
Worked example
Waist 70 cm, ease 2 cm, full circle skirt 60 cm long, 2 cm hem: R_waist = (1 x 72) / (2 x pi) = 11.5 cm. R_cut = 11.5 + 60 + 2 = 73.5 cm. Fabric square = 2 x 73.5 = 147 cm x 147 cm. Hem circumference = 2 x pi x 73.5 = 462 cm.
What is a circle skirt?
A circle skirt is cut from one or more pieces of fabric shaped like a ring (annulus). The inner arc follows the waist and the outer arc becomes the hem. Because the grain of the fabric runs in every direction around the hem, circle skirts have a characteristic fluid flare that falls evenly without pleats or gathers. The amount of flare depends on the fraction of a circle used: a full-circle skirt uses a complete ring and gives maximum volume, a half-circle skirt uses a semi-ring for moderate flare, and a quarter-circle skirt gives a subtle A-line. A 3/4 circle sits between full and half in both volume and fabric consumption.
The radius formula explained
The waist of the skirt is an arc of the inner circle. For a full circle the entire circumference equals the waist, so waist = 2 x pi x R, which gives R = waist / (2 x pi). For a half circle only half the circumference forms the waist opening, so you need a larger radius to fit the same waist: R = 2 x waist / (2 x pi). In general, R = (multiplier x waist) / (2 x pi), where the multiplier is 1 for a full circle, 4/3 for a 3/4 circle, 2 for a half circle, and 4 for a quarter circle. You then add ease (comfort room at the waist) before dividing, and add the skirt length and hem allowance to get the full cutting radius.
How to cut a circle skirt from the calculated dimensions
Fold your fabric into quarters so that one corner is the selvage-and-fold corner. Pin the layers to stop them shifting. Attach a string or tape measure to a pin at the corner (this is your pivot point). Mark the inner arc at the waist-radius distance, then mark the outer arc at the cutting-radius distance. Cut along both arcs through all layers. When unfolded you have a complete ring. For a half-circle skirt fold the fabric only once (in half), and for a quarter-circle skirt cut from a single layer. Always cut on grain so the centre-back and centre-front seams run straight of grain.
Seam allowance, ease and hem allowance
This calculator separates ease (comfort at the waist), seam allowance (the fabric taken up by stitching the waistband), and hem allowance (the fold at the bottom). Ease of 2 cm (about 3/4 in) is standard for a fitted waist; increase to 3-4 cm if the skirt needs to pass over the hips when dressing. The standard dressmaking seam allowance is 1.5 cm (5/8 in). Hem allowance depends on the hem method: 2 cm suits a double-fold machine hem, 5 cm suits a deep blind hem, and 0.6 cm suits a narrow rolled hem on a serger. Stay-stitch the waist arc immediately after cutting to prevent the bias edges from stretching before you attach the waistband.
Skirt length reference guide
| Style | Length (cm) | Length (in) | Notes |
|---|---|---|---|
| Mini | 38-45 | 15-18 | Mid-thigh to just above the knee |
| Above-knee | 48-52 | 19-20 | Just above the knee |
| Knee-length | 55-58 | 21-23 | At or just below the knee |
| Midi | 75-90 | 29-35 | Calf to lower calf |
| Maxi | 100-115 | 39-45 | Ankle to floor-length |
Approximate finished lengths measured from the waistband seam, for adults.
Frequently asked questions
How do I measure my waist for a circle skirt?
Measure around the part of your torso where you want the waistband to sit, usually the narrowest point between the ribs and hips. Hold the tape snug but not tight and breathe normally. Do not add ease yourself - enter the actual measurement and use the Ease field to add comfort room.
What is the difference between a full, half and quarter circle skirt?
The fraction tells you how much of a complete circle the pattern piece is. A full-circle skirt uses a complete ring and gives the most flare and volume. A half-circle skirt uses a semi-ring, giving moderate flare with less fabric. A quarter-circle gives a subtle A-line flare. A 3/4 circle sits between full and half. Because each type divides the circumference differently, a smaller fraction requires a larger radius to enclose the same waist measurement.
Do I need to add seam allowance separately?
This calculator includes separate controls for seam allowance (at the waist) and hem allowance (at the outer edge). The waist radius shown already accounts for them. The cutting radius includes the hem allowance added outward. The seam allowance at the waist is added inward when you cut, so the seamline sits at the waist-radius distance from the pivot.
How much fabric do I need for a circle skirt?
The calculator gives you the side length of the square of fabric needed (2 x cutting radius). For a full-circle skirt you fold fabric into quarters and cut one quarter-ring, which opens into a full ring, so you need a square whose side equals twice the cutting radius. For a half-circle skirt you only need a rectangle twice as long as the cutting radius and as wide as the cutting radius. Many fabric shops sell fabric in standard widths (112 cm, 140 cm, 150 cm); check whether the fabric square fits before buying.
Can I use this calculator for a gathered or pleated skirt?
No. Gathered and pleated skirts are rectangles with a width equal to the waist multiplied by a fullness factor (typically 1.5 to 3x for gathers). A circle skirt is cut as a ring and gets its flare from the fabric grain, not from gathers. Use this tool only for circle-style pattern pieces.
What seam allowance should I use?
The standard dressmaking seam allowance in metric countries is 1.5 cm (5/8 in in imperial). If you are working with a home-sewing machine that has a standard presser-foot guide, 1.5 cm will work with most guides. Use 1 cm if your fabric frays little and you want to save material; increase to 2 cm if you need extra room for fitting adjustments.