Construction Tools
The math behind seams, hems, gathers, elastic, buttons, binding, and darts. Each tool gives you the exact measurements so you can cut and sew with confidence.
Seam Allowance Calculator
Convert between Burda (none), US 5/8", French 1/2", and more — with step-by-step instructions.
Hem Allowance Calculator
Narrow, double-fold, blind, faced, rolled, or topstitched — the exact allowance and pressing steps.
Gathering Calculator
How much fabric for gathered skirts, ruffles, and sleeves? Choose a ratio, get the cut length.
Elastic Calculator
Cut length by elastic type (woven, knit, clear, swim) and tension — not just 80%.
Button Spacing Calculator
Evenly space buttons with one always at bust level to prevent gapping.
Bias Binding Calculator
Cut strip width, total length, continuous bias method, and how many packages to buy.
Dart Manipulation
Move a dart from side seam to shoulder, waist to armhole — the angle stays, the width changes.
Getting construction details right
Most patterns tell you what seam allowance to use but not how to adapt when you need a different one. They specify a hem style but don't calculate the allowance for you. These tools fill in the gaps so you spend less time doing arithmetic and more time sewing.
If you're working with a Burda pattern (no seam allowance included), start with the Seam Allowance Calculator. If your pattern calls for gathering or elastic, use those tools before cutting to know exactly how much fabric you need.