You've been wearing the same bra size for years — but have you ever wondered if it's actually right? Studies show that up to 80% of women wear the wrong bra size. The good news? Finding your true fit is easier than you think, and it starts with understanding sister sizing.

What Is Sister Sizing?

Sister sizing is a method of finding equivalent bra sizes that share the same cup volume but differ in band length. Think of it as a "family" of sizes — they're related, and one might feel significantly more comfortable than another, even though they're technically similar.

Here's the key rule: When you go up one band size, go down one cup size (and vice versa). The cup volume stays roughly the same.

How to Measure Yourself at Home

You only need a soft measuring tape and a mirror. Here's the step-by-step process:

Step 1: Measure Your Band Size

1. Wrap the measuring tape snugly around your ribcage, directly under your bust
2. The tape should be level all the way around — check in the mirror
3. Exhale normally and take the measurement
4. If the number is even, that's your band size. If odd, round up to the next even number

Step 2: Measure Your Bust Size

1. Wrap the tape around the fullest part of your bust (usually at the nipple line)
2. Keep the tape snug but not tight — you should be able to fit a finger underneath
3. Make sure the tape is parallel to the floor

Step 3: Calculate Your Cup Size

Subtract your band size from your bust measurement. Each inch difference equals one cup size:

Signs You're Wearing the Wrong Size

• Band rides up in the back — Your band is too large. Try a smaller band with a larger cup (sister size up).
• Straps dig into shoulders — The band isn't doing its job. Most support comes from the band, not the straps!
• Cup overflow or gaping — The cups are the wrong size. Try your sister size with a different cup.
• Underwire pokes or doesn't lay flat — This usually means the cup is too small or the band is too loose.
• Breasts spill out the sides or bottom — Classic sign of a band that's too large and cups that are too small.

The Sister Sizing Chart

Use this reference to find your sister sizes quickly:

When to Get Re-Measured

Your body changes, and so should your bra size. Get re-measured:

• After significant weight gain or loss (10+ lbs)
• During or after pregnancy
• After starting or changing a workout routine
• Every 6-12 months, just to be sure

Finding Your Perfect Fit at AngelofYou

Every AngelofYou bra is designed with real women in mind. Our size range spans from 30A to 44G, and each style is tested across multiple body types to ensure comfort and support at every size.

Whether you're looking for a supportive everyday bra, a wireless comfort style, or something a little more special, our complete bra collection has something for you.

Written by the AngelofYou Intimates team. For sizing questions, email us at [email protected].