An estimated 8 in 10 women wear the wrong bra size — and almost every comfort complaint we hear (digging straps, riding bands, spilling cups) is actually a sizing problem in disguise.
The fix takes two minutes and a soft measuring tape. No fitting room required.
Step 1: Measure your band
Stand up straight, breathe out normally, and wrap the tape around your ribcage directly under your bust. It should be snug — tighter than feels natural for a shirt.
Round to the nearest even number. That's your band size. Don't add inches — that advice dates from pre-elastic bras. Adding 4 inches to your measurement is the single most common reason bands ride up.
Step 2: Measure your bust
Wrap the tape around the fullest part of your bust, keeping it level across your back. Don't compress the tissue — the tape should rest, not squeeze. If your breasts are asymmetrical (most are), measure the larger side.
Step 3: Calculate your cup
Subtract your band measurement from your bust measurement. Each inch of difference is one cup size:
- 1" = A • 2" = B • 3" = C • 4" = D • 5" = DD/E
Example: bust 37", band 34" → 3" difference → 34C.
Step 4: Know your sister sizes
If a bra fits in the cup but not the band, don't change the cup volume — use a sister size: go down a band and up a cup (34C → 32D), or up a band and down a cup (34C → 36B). Same cup volume, different fit around the body.
The 5 fit checks that confirm your size
- Band level: parallel to the floor all the way around. Riding up = band too big.
- Loosest hook: a new bra should fit on the loosest hook, leaving the tighter ones for when the elastic relaxes.
- Center panel flat: the piece between the cups should touch your sternum.
- No spillage, no gaping: tissue spilling over = cup too small; wrinkled fabric = too big.
- Two-finger straps: you should slide two fingers under each strap — no more, no less.
Sizing notes by bra type
- Wireless bras — like our Wireless Push-Up 3-Pack — fit true to your measured size. Resist the urge to size down for "more support"; that's the band's job.
- Strapless — go one band size down (full explanation in our strapless guide).
- Larger cups — prioritize wide bands and full coverage, like the Wide-Band Wireless Support Bra.
- Between sizes? Choose the snugger band and the roomier cup.
FAQ
How often should I re-measure?
Every 6 months, or after any weight change of ~10 lbs, pregnancy, or starting/stopping hormonal medication. Band size shifts more often than people expect.
Why do different brands fit differently?
Cut and fabric stretch vary. Your measurement is the starting point; the 5 fit checks above are the real test.
My band and cup measurements seem right but the bra still hurts. Why?
Check the style, not the size — wire placement, cup depth and strap position differ by design. Our wireless vs. underwire guide helps you pick the right structure for your shape.