Sewzy
To adjust a sewing pattern to fit you, measure your body, compare the numbers with the pattern's body size chart, and pick the size by the measurement that is hardest to change: your bust for tops and dresses, your hip for skirts and pants. If you fall between sizes, blend two sizes, change the length at the lengthen and shorten lines, and test the fit on a scrap or a toile before you cut your good fabric.
TL;DR
- Measure your bust, waist and hip in thin clothes, with the tape level and snug but not tight.
- Compare with the body column of the size chart, not the finished garment column.
- Choose by the bust for tops and dresses, and by the hip for skirts and pants.
- Between sizes: blend by drawing a smooth line from one size to the other, or choose the nearest size for loose styles.
- Change length on the lengthen and shorten lines, then test on a toile or scrap.
Sew the Boxy Tee from this guide, step by step, in the Sewzy app
Pick your size, print it from your phone, and follow every step with a sewing coach beside you.
The method, step by step
- Measure. Bust is around the fullest part of the chest. Waist is around the natural waist, the narrowest part. Hip is around the fullest part of the hips and seat, which is often lower than people expect. Write the numbers down.
- Compare with the size chart. A pattern gives body measurements (you) and finished measurements (the garment). The gap between them is ease. Match your numbers to the body column. Our guide to what size sewing pattern you need goes into detail.
- Pick the deciding measurement. Shoulders and chest are hard to alter, and the bust tracks them, so tops go by the bust. A waist can be taken in or let out, and an elastic waist forgives a lot, but a hip that is too small is hard to fix, so skirts and pants go by the hip.
- Grade between sizes if you need to. If your bust and hip land in different sizes, cut one size at the bust and draw a smooth line to the other size at the hip.
- Change the length. Use the lengthen and shorten lines on the pattern piece.
- Test. Sew a toile or a scrap version before you cut the real fabric.
Not sure of your size on a standard chart? The sewing pattern size calculator turns your bust, waist and hip into a size. Indie patterns often differ from a standard chart, so always check the chart printed on your own pattern.
Fixes for common situations
| Situation | What to do | Fact or judgment call? |
|---|---|---|
| You are between two sizes in a loose, boxy style | The smaller size is usually fine, because there is a lot of ease | Judgment call |
| You are between two sizes in a fitted style | Take the larger size and take it in | Judgment call |
| Bust and hip are in different sizes | Cut one size at the bust and draw a smooth line to the other size at the hip | Standard method |
| The garment is too short or too long | Cut along the lengthen and shorten lines and spread or overlap the paper by the same amount | Standard method |
| A child's pattern is labeled by age | Choose by the chest measurement on the chart, then adjust the length at the hem | Standard method |
| You are not sure the fit is right | Sew a toile or scrap version first and try it on | Good practice |
A worked example
The free Boxy Tee has a size M for a 37 inch bust and a size L for a 40 inch bust. Say your bust is 38 inches. You fall between the two.
The finished tee in size M measures 47 inches around, which is 10 inches of ease. With that much room, size M is a sensible choice for a relaxed look. If you want a little more room at the arms, size L is just as reasonable. Neither is wrong, and that is why this is a judgment call.
For a skirt, you would check your hip instead. The Elastic-Waist Skirt is chosen by the hip, with size M for a 41 inch hip.
Changing the length
Most patterns mark a pair of lines across the piece for lengthening and shortening. Cut along them and spread the paper to add length, or overlap it to remove length, by the same amount. Do the same on the front and the back so the side seams still match. Our guide to reading a sewing pattern shows these marks.
A hem is easier. For simple pieces such as a skirt or a tee, you can often change the length at the hem. Keep the hem edge parallel to the original so it hangs level.
Test before you cut
A toile is a test version in cheap fabric of a similar weight. Sew it with long stitches, try it on and mark what needs to change on the fabric. For a simple, loose piece, a scrap test of one seam may be enough.
Watch your seam allowance, too. A seam sewn ⅛ inch too wide takes ¼ inch from the finished width, because both pieces lose ⅛ inch. Use the allowance the pattern states. The seam allowance guide has the common widths.
The Sewzy app for iPhone has a size finder that gives a size from your bust, waist and hip, and each pattern lists its own body measurements so you can compare them before you cut.
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