Use your high bust measurement if the difference between it and your full bust is more than about 2 inches (5 cm), and your pattern is drafted for a B cup. That is the case with most commercial patterns. Then adjust the bust area of the pattern. If your pattern company drafts for a larger cup size, or the garment is loose and unstructured, your full bust may work fine. Check the pattern's own size chart before deciding.
Why high bust often works better
Your high bust is measured around your chest above the bust, under the arms and straight across the back. It reflects your upper frame, which sets the fit of the shoulders, neckline and armholes. These areas are hard to fix once a garment is cut. Extra room over the bust is much easier to add than to remove from the shoulders.
How to measure
- Wear the type of bra or undergarment you will wear with the finished piece.
- Measure your full bust at the fullest point, keeping the tape level around your back.
- Measure your high bust snugly above the bust, with the tape level.
- Subtract the high bust from the full bust to see which approach fits your pattern.
Which measurement to use
| Your situation | Usually go by | Tradeoff |
|---|---|---|
| Difference is about 2 in (5 cm) or less | Full bust | Little or no adjusting, but check the shoulders |
| Difference is larger, pattern drafted for a B cup | High bust, then adjust the bust | Better shoulders and neckline, but you need to alter the pattern |
| Pattern offers cup size options | The cup option matching your difference | Less pattern alteration, but the options vary by company |
| Loose, boxy or stretchy design | Either, depending on the ease you want | Forgiving, but the drape may change |
Caveats
Companies draft differently, and the chart and cup assumption are not always on the envelope. Look in the pattern description or the designer's fit notes. If you cannot find them, treat the pattern as drafted for a B cup and confirm on the designer's official site. Ease also changes how a size feels, so read the finished garment measurements as well as the chart.
A test garment is the best way to confirm your choice. Our answer on whether you need to sew a muslin first explains when it is worth the time.