Dart Manipulation
Want to move a bust dart from the side seam to the shoulder? Or from the waist to the armhole? Enter your original dart dimensions and target position — we'll calculate the new dart width (preserving the fit) and give you step-by-step slash-and-spread instructions.
Dart Positions
Your Existing Dart
Measure on the pattern piece. Width = the gap between the two dart legs at the seam edge (not the folded depth). Length = from the seam edge to the tip, not including seam allowance.
Target Seam Distance
On your pattern, measure from the bust apex to the waist seamline (not the cutting line). This determines how wide the new dart will be.
Why move a dart?
All darts on a bodice front point toward the same place — the bust apex. A side seam dart, a waist dart, and a shoulder dart all remove exactly the same amount of fabric; they just remove it from different edges of the pattern. This means any dart can be rotated to any other position without changing the fit.
Common reasons to move a dart: the design you're making has no dart (you need to convert to ease or gathers), you prefer a style detail at a different location, or the existing dart position is hard to sew cleanly at a particular fabric.
What the dart angle tells you
The dart angle — the wedge of fabric being removed — stays constant regardless of position. What changes is the width at the seam edge: a dart pointing toward a seam that's close to the apex will be narrow; a dart pointing toward a seam that's far from the apex will be wide.
As a rule of thumb: if the new dart width exceeds about 1½", it's worth dividing into two smaller darts placed side by side. Two darts of ¾" each will lie flatter and press more easily than a single dart of 1½".
Converting a dart to ease or gathers
Instead of sewing the new dart as a dart, you can distribute the intake as ease (for small amounts, typically under ½") or gathers. To convert: follow the slash-and-spread steps above, but instead of sewing the dart legs together, ease or gather that section of the seam when joining it to the adjoining piece.
This technique is commonly used at the cap of a sleeve (ease eased into the armhole), at yoke seams, and at necklines. The fabric is physically shorter, so the seamline must be eased in — the body curves hold the extra fabric.
Finding the bust apex on your pattern
The apex is the point where all dart legs converge. On most commercial patterns it's marked with a dot or crosshairs. If it isn't marked, extend both legs of an existing dart inward — they'll meet at the apex.
On your body, the apex corresponds to the fullest point of the bust. The pattern's apex may be placed slightly higher or inward for a better silhouette — especially on patterns that grade for a B cup. If you've done an FBA, your apex may have moved; re-check its position on the adjusted pattern before manipulating darts.