The following information should help make determining bra size easier. 
However, because bust shapes, bust positions on the body, and bra styling vary, the precise bra size cannot be determined without a fitting. 
Measure your bust circumference loosely,
measure your chest circumference, under the bust, as tight as possible without indenting the skin.

Measure your bust and your chest circumference

Take two measurements, the bust circumference and the chest circumference. Wear only a bra. If one wears even a tight knit undergarment it can add an inch to the circumference.
The bust circumference should be measured loosely, hold the tape measure around the full of the bust as loose as possible, but just tight enough so that the tape does not fall down.
The chest circumference should be measured as tight as possible without indenting the skin. 
Add five inches to give the bra size’s circumference measurement. 
Bra companies determine a woman’s bra size by first measuring the chest under the bust, 
then adding five inches to give the bra size’s circumference measurement. 
 Cup size nomenclature is related to bust circumference.
The same cup size in the next largest bra or pattern size is given the previous letter.
 For example: The size C cup in a 34 bra is a size B cup in a 36 bra.
The size B cup in a 36 bra is a size A cup in a 38 bra.

Determine your cup size

If your bust measures the chest size plus 5 inches, your cup size is a C, the average cup size in each bra size. 

For example: A woman with a 31 inch chest adds 5 inches to determine that she wears a bra with a 36 inch circumference. If her bust measures 36 inches she wears a C cup. If her bust measures one inch less – 35 inches, she wears a B cup; one inch more – 37 inches, a D cup.

The Relationship Between Home-sewing Pattern’s and Bra Sizing

The commercial pattern companies use the same system, but traditionally draft their patterns with a B cup. Their sizing charts give a bust measurement two inches larger than the chest measurement – an AA cup size, but because the pattern’s bust measurement is four inches more than the chest measurement the pattern’s true cup size is a B. 

This information is from Grading to Fit, a book currently in progress that hopefully will be on the market before the end of the year.

Keep watching, the website at is currently being professionally upgraded, the new website should be online in early March, 2018.

Bye for now, thanks for reading – Laurel


Phone: 215 884 7065
© Laurel Hoffmann, 2018. 

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