Pattern sizes are not standardised. A “medium” in one pattern can be a “large” in another, and two patterns with the same size label can have different finished measurements. The reliable way to choose is to work from your body measurement, the ease you want, and the pattern's schematic.

The three numbers

  1. Your body measurement. For a sweater, the bust or chest is usually the governing number.
  2. The ease you want. Fitted, classic or oversized; the difference between body and finished garment.
  3. The pattern's finished measurement. From the schematic, not the size label.

Target finished chest = body chest + ease. Find the schematic size closest to that figure.

A worked example

Body chest 96 cm. You want 8 cm of positive ease, so the target is 104 cm.

The pattern offers finished chests of 92, 98, 104 and 110 cm. Choose the 104 cm size. The 98 cm size gives 2 cm of ease — a fitted look; the 110 cm size gives 14 cm — a looser garment.

Then check the other measurements. If the 104 cm size has a 56 cm body length and you prefer 60 cm, you can lengthen the body. If the sleeve is 42 cm and you need 46 cm, adjust the sleeve. Choosing the size is the first decision; the adjustments come after.

If you are between sizes

  • Choose by ease, not by label. Pick the finished measurement that matches the fit you want.
  • Check the fabric. A drapey yarn can tolerate more positive ease; a dense fabric can look stiff when oversized.
  • Check the armhole and sleeve. Sizing up changes the armhole depth and sleeve width; make sure those still fit.
  • Adjust the length. It is usually easier to lengthen or shorten a body than to re-grade an armhole.

Size labels are not measurements

“Small”, “medium” and “large” are convenience labels. Some patterns grade by bust, some by a combination of bust and hip, and some use a different body measurement entirely. Always read the size chart and the schematic before choosing.

Children and growing bodies

For children, choose a size with a little more ease than an adult garment, and check the sleeve and body length against the child's measurements. A garment that fits exactly today may not fit in three months. Record the date with the measurements.

Common mistakes

  • Choosing the size you “usually wear” without checking the finished measurements.
  • Using the body measurement as the finished measurement.
  • Ignoring the sleeve and body length because the chest fits.
  • Assuming the sample garment's ease is the pattern's ease; the sample may be a different size.

Measure a garment you own

Lay a sweater you like flat, measure it across the chest and double it. Compare that number with the pattern's finished chest. This captures the ease and fabric you actually wear, which is often more useful than a size label or an ease table. If the pattern has no schematic, use the size chart with more caution.

When to size up or down

Size up if you want more layering room or a looser fit; size down if you want a closer fit. Check the armhole and sleeve before committing, because sizing up also widens the shoulders and sleeve. If only the body needs to be wider, adjust the body rather than the whole garment.

Limits

A size chart is a guide, not a guarantee. Posture, layering and personal preference all affect what feels right. Measure a garment you already like and compare its finished measurements with the pattern; that is often the most reliable check.

Compare the finished measurements with your body and the intended ease.

Sources