Bra Fitting

How to Find Your Perfect Bra Band Size

If your bra band keeps riding up your back, the straps dig into your shoulders, or you find yourself adjusting your bra throughout the day, the problem is almost certainly your band size. The band is the foundation of a bra — it provides up to 80% of the support. Getting it right changes everything.

1. Why the Band Matters More Than the Cup

Most people focus on cup size when shopping for a bra, but the band is where fit actually begins. A correctly fitted band sits straight and level across your back, parallel to the front. If the band rides up, it means the band is too loose — and the bra is failing to support you properly.

2. How to Measure Your Band Size

You will need a soft measuring tape. Follow these steps:

1. Wrap the measuring tape snugly around your ribcage, directly under your bust.
2. Keep the tape level — it should be straight all the way around, not angled.
3. Breathe out naturally and take the measurement. Do not pull the tape too tight or leave it too loose.
4. Write down the measurement in centimeters.

This number is your underbust measurement, which determines your band size.

3. Converting Your Measurement to a Band Size

Underbust (cm)	Japanese Band Size	US Band Size	UK Band Size
63–67 cm	65	30	30
68–72 cm	70	32	32
73–77 cm	75	34	34
78–82 cm	80	36	36
83–87 cm	85	38	38
88–92 cm	90	40	40

4. How a Correctly Fitted Band Should Feel

• The band should sit flat and straight across your back at the same level as the front underwire.
• You should be able to fit two fingers underneath the band — no more, no less.
• The band should feel snug but not painful. You should be able to breathe comfortably.
• When you raise your arms, the band should not move upward.
• On a new bra, always start on the loosest hook. As the bra stretches with wear, you can move to tighter hooks to extend its life.

5. Signs Your Band Size Is Wrong

Problem	Likely Cause	Solution
Band rides up at the back	Band too loose	Go down one band size
Band feels painful or leaves marks	Band too tight	Go up one band size
Straps dig in constantly	Band not supporting — straps compensating	Go down one band size
Band gaps away from body	Band too large	Go down one band size

6. The Sister Size Rule

If you change your band size, you need to adjust your cup size accordingly to maintain the same cup volume. This is called sister sizing.

7. Japanese Band Sizing vs US Sizing

Japanese bra bands use centimeter measurements (65, 70, 75, 80) while US sizing uses inches (30, 32, 34, 36). Japanese sizing tends to run truer to your actual underbust measurement, which many women find more precise and comfortable than the US system. If you have struggled to find your perfect fit in Western brands, Japanese sizing may be the answer.