How do I move a dart on a pattern?

A dart can be moved anywhere around the piece by rotating it about the point it shapes — close the old dart and an identical amount of space opens where you cut the new one.

The principle. A bust dart takes flat fabric and gives it a cone shape over the bust. The volume of that cone is fixed; where the fold enters the piece is entirely a design choice. That is why one bodice block produces side darts, waist darts, French darts, neckline darts and shoulder darts.

The method. Mark the bust point — the apex of the cone — a little inside where the existing dart legs would meet if extended. Draw a line from the new dart position to that point and cut along it. Then close the original dart by bringing its two legs together and taping them. The piece pivots and the new cut swings open by exactly the amount that was folded out. Tape a paper strip behind the opening and draw in the new dart legs.

Shorten the new dart so its point stops 20 to 30 mm short of the bust point. A dart sewn right to the apex creates a hard point; ending short lets the shaping soften.

Splitting one dart into two works the same way: cut two lines and let each take half the rotated volume.

Check the piece still fits its neighbours. Rotation changes the outline, so walk every affected seam afterwards and true the edges through the new dart.