Blouse Fit & Dart Ease Calculator
Add the right ease to your bust and waist, then split the bust-to-waist taper between the side seams and the waist darts — the numbers behind a well-fitted blouse.
Finished measurements & darts
Ease is the room the blouse needs beyond the body. Half the bust-to-waist taper is shaped at the side seams and half in the waist darts — a rule of thumb your tailor will refine on a trial fit.
From body to pattern
A blouse that fits well is never cut to the raw body measurement. First you add ease — a little for a fitted look, more for a relaxed one — to get the finished bust and waist the garment should measure. Then, because the finished bust is wider than the finished waist, the pattern has to taper, and that taper is shaped out with the side seams and the darts.
This calculator does both steps: it turns your measurements into finished ones and then splits the taper into a per-seam and per-dart figure you can mark straight onto the pattern. It gets a draft close so the trial fit is a tweak, not a redraw.
Frequently Asked Questions
What is ease, and why add it?
Ease is the room a garment needs beyond your body measurements so you can breathe, move, and let the fabric drape. A blouse cut to your exact bust would strain at the seams. This tool adds a bust ease of 5cm for a fitted look, 10cm for semi-fitted, or 15cm for relaxed, and a smaller ease at the waist, to turn body measurements into finished-garment measurements.
What is dart intake?
It's the total amount the blouse has to taper as it narrows from the finished bust to the finished waist. That taper can't just vanish — it's taken out of the cloth by shaping the side seams and by sewing darts. The intake figure is that total; the tool then splits it so you know how much each seam and each dart should remove.
How is the taper split between seams and darts?
As a common rule of thumb, about half the taper is shaped at the two side seams and half is taken up by the waist darts. The tool divides the side-seam share across the two seams and the dart share across however many front waist darts you choose, giving a per-seam and per-dart figure to mark on the pattern.
Is this a substitute for a fitting?
No — it's a starting point for drafting. Ease preferences are personal, fabrics behave differently, and bodies aren't symmetrical, so a tailor's toile or trial fit is where the numbers get finalised. Use the calculator to draft close, then refine on the body.
Educational rule-of-thumb only. Ease preferences and dart placement are personal and fabric-dependent — a tailor’s toile or trial fit is the real test before you cut your final cloth.