Circle Skirt Calculator
Calculate circle skirt geometry: the waist radius to cut for full, half and three-quarter circles, the fabric length needed and the minimum fabric width.
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What this tool does
Calculate circle skirt geometry: the waist radius to cut for full, half and three-quarter circles, the fabric length needed and the minimum fabric width. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
How to use the Circle Skirt Calculator
- Enter or select waist measurement (inches).
- Enter or select finished skirt length from waist (inches).
- Enter or select circle style.
- Read the calculated result; change any measurement to compare alternatives.
Formula
The waist edge is an arc of the circle: radius = waist / (arc angle in radians) — full: waist/(2pi), three-quarter: waist/(1.5pi), half: waist/pi. Fabric length = 2 x (radius + length + 1 in hem) for a full circle cut in one piece; minimum width = 2 x (radius + length).
- waist
- Waist measurement (inches)
- length
- Finished skirt length from waist (inches)
- style
- Circle style
Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
Worked example
For circle skirt calculator, the following measurements illustrate the exact method: Waist measurement (inches): 28; Finished skirt length from waist (inches): 24; Circle style: full.
Inputs
- Waist measurement (inches)28
- Finished skirt length from waist (inches)24
- Circle styleFull circle (360°)
Result
- Waist radius to cut (inches)4.46
- Fabric length needed (inches)58.9
- Fabric length needed (yards)1.75
- Minimum fabric width (inches)56.9
- Hem circumference (inches)178.8
Results explained
- Waist radius to cut (inches)
- Waist radius to cut (inches) from the formula above. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
- Fabric length needed (inches)
- Fabric length needed (inches) from the formula above. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
- Fabric length needed (yards)
- Fabric length needed (yards) from the formula above. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
- Minimum fabric width (inches)
- Minimum fabric width (inches) from the formula above. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
- Hem circumference (inches)
- Hem circumference (inches) from the formula above. Waist is your body waist where the skirt will sit, with no ease or waistband allowance added — add your seam/waistband allowance to the radius cut if your pattern needs it. The 1 inch added is hem allowance.
Frequently asked questions
Divide your waist by the circle's arc: full circle waist/(2pi) — a 28-inch waist gives a 4.46-inch radius. Half circles divide by pi (radius 8.9 in), because the same waist wraps only half a circle.
Length = 2 x (waist radius + skirt length + hem), and the fabric must be at least that wide too — for a 28-inch waist and 24-inch length, about 59 inches long on 59-inch-wide fabric. Narrower fabric means seamed panels.
Bias edges stretch: the parts of the circle cut on the bias grow under the skirt's own weight. Hang the skirt for 24-48 hours before levelling and hemming the hem.
A half circle uses roughly half the fabric width and drapes in soft folds; a full circle is the maximum-flare 1950s silhouette and often needs wide fabric or seams. Three-quarter is the middle ground.
The radius here lands the fabric edge exactly at your waist measurement. If you attach a waistband, subtract the band's seam allowance from the radius or add ease per your pattern — check before cutting the centre hole, which cannot be un-cut.