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Dart Manipulation Calculator
Calculate dart point positions and intake amounts for bodice darts.
How We Calculate This
Dart Angle
Angle = 2 x arctan(Half Intake / Dart Length)
Dart Leg Length
Leg = sqrt(Dart Length² + Half Intake²)
Pivot Method
Closing the original dart causes the new dart to open with the same intake amount. The bust point acts as the pivot centre.
Frequently Asked Questions
Dart manipulation (also called dart rotation or pivoting) is the process of moving a dart from one position to another while keeping the same amount of shaping. The total dart intake stays the same — only the position and direction change. This is a fundamental pattern-making skill.
The dart point should stop 2 to 3cm short of the bust apex (bust point) to avoid a pointed, unflattering shape. This offset creates a smoother, more rounded shape over the bust. The exact offset depends on cup size — larger cups may need 3cm or more.
Yes, you can divide the dart intake between two positions. For example, split a waist dart into a smaller waist dart and a side dart. Each dart takes a portion of the total intake. This distributes the shaping and can be more flattering on larger busts.
A French dart runs diagonally from the side seam (below the armhole) toward the bust point. It creates a slimming diagonal line and is popular in fitted dresses and blouses. The dart entry point is typically at the side seam, halfway between waist and armhole.
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Last updated: March 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.