If you’re struggling to fit a darted front bodice, a princess seam may be the dart equivalent of your dreams.
And, it’s easier to go from darts to princess seams than you might realize.
Keep reading to discover:
- The definition of a princess seam
- What makes princess seams superior to darts for fitting
- The basics of dart manipulation
- Step-by-step photographed instructions for how to transform a dart into a princess seam
Plus, as a bonus, you can download a free mini front bodice pattern piece to practice dart manipulation.
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What is a Princess Seam?
The princess seam crosses over the bust point.
There are two common types of princess seams:
1.) Starts at mid-shoulder, passes over bust point, ends at waist.
2.) Starts at mid-armhole (armscye), passes over bust point, ends at waist.
The princess seam is curved to smoothly cross over body curves (chiefly the bust).
Princess seams absorb dart excess — the part of the dart that’s on the wrong side of the garment. Princess seams replace dart legs; they are a dart equivalent.
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Benefit of a Princess Seam
Seams provide opportunities to fine tune fit. More seams = more opportunities.
Princess seams specifically give sewists the opportunity to refine fit at the bust and abdomen — front body volume — because these seams cross the bosom and belly.
You want seams over areas that are tricky to fit. That way you can adjust width with greater precision vs. adding to or subtracting from the overall circumference.
For example, if you notice horizontal pull wrinkles across the abdomen (but not on the mid-to-lower back), the front bodice needs more width.
If the bodice has princess seams, you could add width to the side front panel and center front panel pattern pieces below the bust point to the waist.
Below you can see the additional width in pink:
If the top doesn’t have princess seams, the best you can do is add width at the side seams, which increases the back width and front width.
In short, you get width where you don’t need it and (probably) not enough width where you do need it.
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Introduction to Dart Manipulation
Now, before we get into seams, we have to start with darts.
What’s the point of darts? (LOL dart point joke.)
Darts shape a 2-D surface (fabric) to curve around a 3-D object (a body).
Without darts, fabric cannot cup a body (unless it’s a knit with negative ease, but we’re not talking about that right now).
The wild thing about darts is that they can be moved all around a pattern piece AND STILL correctly cup curves.
The angle of the dart legs stays the same, too.
Here’s visual proof.
Moving a dart is a two-step process:
1.) Slash at the intended (new) dart location, from the edge of the pattern piece to the bust point. (The bust point is the pivot point.)
2.) Bring together the legs of the old dart. The new dart opens where you slashed.
If you want to transform a one-dart bodice into a two-dart bodice, slash and spread from the edge to the bust point at two locations.
So, instead of one larger dart, you have two smaller darts.
If you want to transform a two-dart bodice into a one-dart bodice, slash and spread from the edge to the bust point at one (new) location and close the two (old) darts.
Now you have one large dart.
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Backing Off Darts
When sewing a bust dart, the dart point (where the two legs meet) IS NOT located atop the bust point.
The dart point is backed off from the bust point 0.5 to 1 inch. If you’re larger of boob (4+ inches of difference between the high/upper bust and full bust), the dart point is backed off about 2 inches. (As always, make a muslin to test how much to back off.)
To make it simple, remember this:
|Difference Between High & Full Bust
|Distance to Back Off Dart Point
|≤ 3 inches
|≥ 4 inches
Here’s what backing off looks like in practice:
Why do you back off darts? Because the apex of the bust is rounded, not pointed.
IMO, Helen Joseph-Armstrong said it best in her ubiquitous textbook, “Patternmaking for Fashion Design”:
“All darts radiate from convex shapes of the figure. The bust is rounded. If the dart is stitched to the end of the pivotal (bust) point, strain lines will appear around the bust, distorting the fit of the garment. The dart should end at a distance from bust point to release fabric (fullness) for the bust mound.”
How to Make a Princess Seam from Any Dart
This tutorial shows how to go from a one-dart bodice to a shoulder-to-waist princess seam.
You also can go from a two-dart bodice (side and waist darts) to a princess seam.
With a two-dart bodice, slash from the shoulder to the bust point to separate the side panel and the front panel; the leg of the waist dart is like the slash from the bust point to the waist in the one-dart example.
Also: As you now know, you can move darts around the bodice. Should you have a dart (or darts) in a different location than the side, slash at the side dart location and close the old dart.
Then you’re ready to create a princess seam.
On to the tutorial, which is adapted from the Helen Joseph-Armstrong fashion design textbook.
Here’s our starting point; ignore the dart location lines (they’re not important for creating a princess seam).
Be aware that these pattern pieces do not have seam allowances.
📂 If you’d like to play along , click here to download the pictured small-scale front bodice pattern piece. 👩💻
Draw a line from the midpoint of the shoulder to the bust point.
Draw a line from the bust point to the midpoint of the waist.
Add two match points: one above the bust point and one below the bust point.
Do not forget this step! It will be difficult to sew this seam without the match points.
Cut along the line from the shoulder to the bust point to the waist.
Back off the dart point (see table above for guidance). Redraw the dart legs.
(I retraced the side panel so there was excess on which to back off the dart. This is what your side panel pattern piece probably looks like anyway.)
Slash from the (old) bust point to the new backed-off dart point. (The backed-off dart point is the new pivot point.)
Cut out the dart excess and close the dart legs.
Trace the side panel on a new piece of paper. Shape the bust curve.
Walk the seam from the shoulder to the upper match point and from the waist to the lower waist point.
Walk the seam between the upper and lower match points. The side panel seam between the match points (over the bust) is slightly longer than the front panel seam.
The side panel seam will need to be eased into its counterpart.
Add seam allowance, and center the grainline on the side panel, like this (from HJA).
Final Thoughts About Princess Seams vs. Darts
When it comes to princess seams vs. darts, princess seams give bodies, especially voluminous bodies, a better fit. The princess seam lets you send additional width to specific locations in a way that a dart cannot.
It takes a little extra work to convert darts into a princess seam, but it’s an exercise worth your while to refine a garment’s fit.
Over to you: What’s your experience sewing (and wearing) garments with princess seams? What other questions do you have about transforming darts to princess seams? Let me hear you in the comments! Thanks for reading.
P.S. Don’t forget to download your dart manipulation practice worksheet.