About this tool

Make the allowance directions visible.

Skirtmark helps with one drafting question: where are the waist and hem cut arcs for a full-circle panel when the stitched opening and finished radial length are already chosen?

The waist allowance belongs inward from its seamline, while the hem allowance belongs outward from its intended finished line. Showing those circles together helps prevent a common drafting mix-up. The result includes the minimum flat square envelope and an area, each clearly distinguished from yardage to buy.

One calculator, with supporting explanation

This independent website contains one browser-local calculator and original method, example, privacy and contact pages. It models one unbroken full circular ring, not half or quarter circles, joined panels, closures, waistband pieces or an automatic garment-fitting service. The chosen opening must be appropriate for the user's own construction and hip clearance.

Approximate geometry

The calculation uses finite numerical arithmetic and Math.PI. Results are approximations, even when the display shows several digits. There is no print-to-scale export or physical cutting-accuracy promise. The guide explains the formulas, parser and model; the worked examples make the opposite allowance directions easy to check.

Free use and current settings

No account or payment is required. This source release includes no active advertising, analytics or consent-platform loaders. Advertising could be introduced only after exact-host configuration and applicable consent coverage are verified. Publisher metadata and ads.txt do not mean that ads have been approved or are serving. No traffic or earnings are promised.

Corrections

Use the shared public contact address to report a reproducible numerical or wording issue. State the Skirtmark name, entered centimetre values and expected result. A small non-sensitive example is enough; personal measurements are optional and should not be sent unless you want to share them.