how to measure bra size

The band size of bra

Your bra size exists of two measurements. The cup size is determined by measuring the fullest part of your breasts. The band size of your bra is the result of measuring your underbust.

  • How to measure your bra band size
  • How tight should a bra band be?
  • What if I’m in between two band sizes?

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How to measure your bra band size?

There are about 14 different band sizes available. Although not every brand has the whole range of band sizes 28 – 54. The smaller the band size you need, the smaller your underbust is.

For the band, measure directly under your bust. Hold the measuring tape horizontal, looking in a mirror will help.

My advice is to measure a couple of times and write down the outcome. It’s normal if you measure slightly different numbers because it depends on how tight you hold the measuring tape. By measuring a couple of times you’ll learn just by practicing.

Find more topics on measuring your bra size here »


How tight should a bra band be?

  • Your band size should be firm but not too tight.
  • When you wear your bra for some time the band should still feel firm but comfortable.
  • Do remember that the most support of your bra comes from the band.
bra band size too big
The most support from your bra comes from its band

When you choose a bra the first thing you decide on is your band size. From there you choose your cup size. It could be your measurements are in between two band sizes. You could round up to the nearest whole number.


What if I’m in between two band sizes?

I wear the band sizes 34 and 36. Depending on the brand I might choose a different bra band size. And all the bras fit me just fine. However. Going up or down a band size will automatically change the cup volume as well.

Depending on your measurements you can wear perfectly happy two different bra sizes. They are called sister sizes. For example, a 36C and a 38B could be the sister sizes of one woman. Another woman could have 36C and 34D as her sister sizes.

bra band size chart with sister sizes
Example of sister sizes

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This happens when you go up a band size

You wear a bra 36C and want to go up a band size. You choose a band size 38. But when going up a band size the volume of the cups will change too. A 38C bra will have bigger cups, and broader set, than the bra in 36C.

If you want to keep the same cup size you should try 38B.


This happens when you go down a band size

You wear a bra 36C and want to go down a band size. You choose a band size 34. But when going down a band size the cups will change too. A 34C bra will have less cup volume than a bra in 36C.

If you want to keep the same cup size you should try 34D.

Different brands may be sized a bit differently. If you know your bra sister size you know easily what bra sizes to try.

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