Craft and sewing calculators
Pattern drafting is geometry with a seam allowance. A circle skirt is the clearest case: the waist radius comes straight out of the circumference formula, and everything that goes wrong afterwards comes from fabric width, nap direction and how the pieces are laid out rather than from the maths.
1 calculators in this section
Metres, not yards
Fabric in Australia is sold by the metre, and bolt widths here are usually 110, 115 or 150 centimetres. A yardage figure from an American pattern calculator is not just a unit conversion away from useful, because the layout that fits on a 45-inch bolt is not the layout that fits on a 150-centimetre one.
Other AU sections
The circle skirt radius is the same geometry the maths section uses for circles.