Bra Size Calculator

Keep Your Band Anchored

Stop your bra band from creeping up with accurate measurements, smarter sister size swaps, and support-first styles.

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Signs Your Band Is Riding Up

These clues mean your band is no longer doing its job. Spot them early to prevent discomfort and keep support balanced.

  • Band sits higher in the back than the front when viewed in a mirror
  • You constantly tighten straps to keep the front in place
  • Cups tilt forward or gap after moving around
  • Straps slip even though they are adjusted tightly

Quick diagnostic tip

Slide two fingers under the band at the back. If it stretches more than two finger widths away from your body, the band is too loose or worn out.

Quick Fixes That Make a Difference

Start on the loosest hook

A new bra should be comfortably snug on the loosest hook. If you need tighter hooks immediately, the band is too big.

Check the band level every month

Elastic stretches. If you can pull the band more than 2 inches away from your body, it’s time to size down or replace the bra.

Match band tension to activity

High-impact days (workouts, long shifts) may require firmer bands or sports bras to keep support anchored.

Measure with the Band in Mind

A level band starts with precise measurements. Follow this checklist before making size changes.

  1. Exhale normally and wrap the tape snugly around your ribcage—parallel to the floor.
  2. Record your underbust measurement in both inches and centimeters if possible.
  3. Measure the fullest part of your bust with relaxed posture; avoid compressing tissue.
  4. Enter both numbers into the calculator using the same unit to find your baseline size.
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Fine-Tune with Sister Sizes

BMW Rule (Band Minus Wire)

If the band rides up but the cup fits, go down one band and up one cup. Example: 36C → 34D keeps cup volume the same.

Hook progression

Start on the loosest hook and move inward only as elastic naturally stretches over time. If you reach the tightest hook quickly, re-measure.

Consider extender as a test

If you are between sizes, use a band extender to gauge comfort before buying multiple bras in the new size.

Styles that Stay Put

Longline bras

Extra band depth provides more grip and keeps the back from creeping up.

Power mesh wings

Firm but breathable fabric reinforces band stability without digging in.

Multi-part cups

Seamed cups distribute weight evenly, reducing the pull that lifts the band.

Sports bras with adjustable bands

Encapsulation sports bras with hook-and-eye closures offer workout-ready support and control band placement.

Set a Maintenance Routine

Elastic is a workhorse. Follow this routine to keep your bands in shape and prevent unexpected fit issues.

  • Rotate at least three bras to avoid over-stressing elastic.
  • Air dry only; heat weakens band fibers.
  • Schedule a monthly five-minute fit check (band level, strap tension, cup coverage).
  • Track body changes (weight, hormones, exercise) that may shift your base size.

Maintenance calendar

Print the band-fit calendar to remind yourself of monthly check-ins. Consistency prevents surprises and keeps support steady.

Download the calendar

Keep Exploring

Fit is interconnected. Use these guides to solve related issues and build a resilient bra wardrobe.

Relieve shoulder strain by rebalancing supportContain side tissue with supportive wings and cupsChoose bands that stay put during workouts

Need tailored advice?

We are building a vetted directory of bra fitters and specialists. Until then, reach out and tell us which resources would help your journey most.

Contact the team

Frequently Asked Questions

Is it normal for a new bra band to feel tight?

A new band should feel snug and supportive, not painful. It will relax after a few wears. If it causes discomfort or restricts breathing, size up in the band.

Can I fix a loose band with strap tightening?

No. Tightening straps only causes digging and won’t keep the band anchored. Always resolve band fit first, then fine-tune straps.

How often should I replace bras to avoid band riding up?

With regular rotation, most bras last 6–12 months. Replace when the band no longer offers firm support even on the tightest hook.