Sister Size Calculator

What Are Bra Sister Sizes?

Sister sizes are bra sizes that have the same cup volume but different band sizes. They're useful when your exact size isn't available or when you want to try a slightly different fit.

How Sister Sizes Work

When you go up in band size, you go down in cup letter, and vice versa. This keeps the cup volume the same. For example:

• 32D = 30DD (sister size down) = 34C (sister size up)
• 36C = 34D (sister size down) = 38B (sister size up)

When to Use Sister Sizes

• Your exact size is out of stock
• A brand runs large or small in the band
• You're between sizes
• You want a looser or tighter band

Sister Size Chart