📐 Dart Intake Calculator

Enter your full bust measurement, the flat pattern front width, and how many darts you're using to see the intake needed at each dart.

Full bust measurement (in)

Flat pattern front width (in)

Number of darts

Intake is the difference, split across the darts

total intake  = full bust - flat pattern width
intake / dart = total intake / number of darts

The defaults - 38 in against a 34 in flat width, two darts - leave 4.00 in of total intake and 2.00 in in each dart. Both figures must cover the same span: two full circumferences, or two quarter-piece widths. The tool only subtracts what you give it.

Measuring the two inputs

Measure the pattern between stitching lines. Cut edges carry seam allowance. A front and back with 5/8 in allowances on both side seams add 2.5 in that is never in the finished garment, and it would wipe out most of the intake.
Add your ease first. The bust figure is a garment measurement, not a body one. Put wearing ease on before you type it - a fitted woven bodice wants 2 to 3 in - or the darts eat the ease.
Two darts beat one big one. Past roughly 1.5 in, a single dart points sharply and bubbles at the tip. Split the same intake between a waist dart and a side bust dart for a softer curve.

Intake is not fixed across a size range. The gap between full bust and underbust widens as sizes go up, so a graded pattern carries a larger dart at 20 than at 12 even though both are drafted for the same cup.

Frequently asked questions

How much dart intake do I need for a bust dart?

Whatever closes the gap between the garment bust and the flat pattern at that level. On a fitted woven bodice 2 to 4 in of total intake is common, usually divided between a side bust dart and a waist dart.

Why is my dart intake coming out negative?

The flat pattern is already wider than the bust figure you entered, so there is nothing to remove. Check that you measured to the stitching line and that both numbers cover the same span before adding ease.

Does dart intake change if I grade the pattern up?

Yes. Grading widens the piece and moves the bust apex outward, so intake grows with the size. Uniform scaling does not do this, which is why an enlarged print fits oddly at the bust.