Dart intake is the total fabric width taken up by darts at a seamline. In pattern drafting, bust dart intake is determined by cup projection (high bust vs. full bust differential), while waist or hip dart intake equals the circumference difference between landmarks minus wearing ease.

How do I measure dart length?

Dart length extends along the fold from the seamline to the dart point. It is calculated by taking the distance from the seam to the bust apex (or contour pivot) and subtracting an apex offset (typically 0.5 to 1 inch or 1.3 to 2.5 cm) so the dart terminates before the apex.

How many darts should I use?

For intakes under 1 inch (2.5 cm), a single dart is standard. For intakes exceeding 1.5 inches (3.8 cm), dividing the intake into two darts distributes shaping more smoothly and eliminates strain.

What units does this calculator use?

You can work in either inches or centimeters. Select your preferred unit before entering measurements. The calculator keeps all outputs in the same unit.

Can I use this for hip or waist darts?

Yes. For waist and hip contouring, intake is calculated from waist-to-hip differentials minus wearing ease, with dart length stopping short of the hip curve or pivot point.

What is dart point placement?

The dart point should stop 0.5 to 1 inch short of the fullest part of the curve (e.g., the bust apex). Stopping short prevents fabric distortion and cone-shaped puckering at the apex.

Dart Calculation (Sewing)

Calculate sewing dart intake, dart length, and apex offset from cup differentials or waist contour measurements for accurate garment drafting.

Dart Measurements

Unit:

Dart Location

Your Body Measurement (inches)

Pattern Measurement (finished, with ease removed)

Darts per Side

Dart Length (leave blank to use recommended)

Dart Results

Enter measurements and click Calculate

How to Mark a Dart on Your Pattern

Mark the intake

Draw the dart legs from the seam edge, each at half the per-dart intake on either side of the dart center line.

Measure the length

From the seam edge, measure inward along the dart center line by the dart length. Mark this as the dart point.

Stitch and press

Fold the dart so the legs meet, stitch from the wide end to the point, then press toward center or downward.

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Summary

Calculate sewing dart intake, dart length, and apex offset from cup differentials or waist contour measurements for accurate garment drafting.

How it works

Select the dart location: bust, waist, or hip contouring.
Enter the differential measurement (high bust vs. full bust for bust darts, or waist-to-hip difference minus ease).
Enter the distance from the seam line to the bust apex or contour pivot.
Choose the number of darts to distribute intake smoothly across the pattern piece.
The calculator outputs total intake, per-dart intake, apex offset, and finished dart length.
Mark dart legs on the seam edge and stitch tapering toward the dart point short of the apex.

Use cases

Adjusting a commercial pattern to fit your bust, waist, or hips.
Converting a muslin fitting ease into precise dart values.
Splitting a single large dart into two smaller darts for a smoother fit.
Calculating waist darts when grading between two sizes.
Teaching pattern-making students the math behind dart manipulation.
Checking dart intake before cutting into fashion fabric.

Frequently Asked Questions

Last updated: 2026-09-20 · Reviewed by Nham Vu