Calculated result
Adjust the editable example, then select Calculate.
Method and assumptions
For fullness fraction f, the waist arc is f × 2πr, so r = waist ÷ (2πf). The finished outer radius is r + finished length. For a seam at the waist, this tool subtracts the entered allowance from the cut inner radius; it adds entered hem allowance to the cut outer radius. The waist circumference is measured at the seam line. No wearing ease is added.
Worked example
A 30-inch waist and 24-inch finished length on a full circle yield a 4.775-inch waist radius and a 28.775-inch finished outer radius before allowances.
Limits of the estimate
The displayed full diameter is a theoretical bounding dimension, not a fabric-width fit guarantee. Grain, folds, panels, directional prints, seams, garment ease, and pattern construction can change actual yardage. This is not a cutting pattern.
Privacy
Measurements and results stay in this browser tab. The calculator does not send input values, store them, or place them in the URL. No account or upload is required.