Patterns fit when finished measurement = your body + the right ease, and every style wants different air. Enter your measurement and the garment; the target finished size comes back: compare it to the pattern’s finished chart, not its size names.
Your Measurement and the Garment
Aim for a Finished
40.5–42in
body 38 + ease 2.5 to 4 in
- Target finished40.5–42.0 in
The Formula
finished garment = body + wearing ease + design easeWearing ease is the air moving needs: about 2 in at a woven bust just to breathe and reach. Design ease is the look on top. Knits replace both with stretch, which is why they run zero and negative.
Worked Example
A 38 in bust sewing a fitted woven blouse (2½–4 in ease):
- Target finished: 40½–42 in.
- The pattern’s finished-bust chart: size 14 finishes 41½, that’s the size, even if its “size” column said 16 by body measurement.
- Between sizes, pick by the fit you prefer and the fabric’s forgiveness: drapey rayon down, crisp poplin up.
Ease by Garment, the Working Table
| Fit | Bust/chest ease | Reads as |
|---|---|---|
| Negative (knits) | −2 to 0 in | Second skin |
| Close fitting | 1–2½ in | Fitted sheath |
| Fitted | 2½–4 in | Tailored blouse |
| Semi-fitted | 4–6 in | Everyday shirt |
| Loose | 6–8 in | Relaxed, untucked |
| Very loose | 8 in + | Oversized, outerwear |
Measuring So the Math Works
- Body: underwear you’ll wear with it, tape level, no breath-holding. Bust at the fullest, waist at the bend, hip at the widest.
- The pattern’s finished measurements live in the chart or printed on the tissue: they’re the only numbers this page compares against. Size names are marketing.
- Copy a garment you love: measure its chest flat, double it, subtract your body: that’s your preferred ease, better than any table.
Assumptions and Defaults
- Ranges are bust/chest ease; waists run tighter (½–1 in fitted), hips between.
- Big-four patterns famously build generous design ease, the finished chart outranks the envelope photo.
- Cup-size adjustments (FBA) change shape, not this target; fit the finished number first.
Ease Questions, Answered
How much ease do I need in a sewing pattern?
A woven garment needs about two inches of wearing ease at the bust just to move, plus the style’s design ease, which the table above runs from negative for knits to 8 in or more for oversized styles. The example blouse takes 2½ to 4 in in total.
Why is my usual size so big in sewing patterns?
Your usual size runs big in sewing patterns because pattern sizes aren’t store sizes: they follow older measurement charts, and the big pattern companies add design ease on top. Choose by the finished measurements against this page’s target, and the size name no longer matters.
What is negative ease in sewing?
Negative ease means a garment is smaller than the body and stretches to fit, which only works with knits. A swim top with −2 in of ease at a 38 in bust, for example, finishes at 36 in, whereas a woven garment at negative ease simply won’t close.
Which way should I go if I’m between sewing pattern sizes?
If you are between sizes in a fitted style, size down and let the fabric’s drape help, whereas loose styles work in either size. Knits and blends forgive the smaller size, crisp wovens don’t, and when the fabric is precious, sew a muslin of the bodice first.