The no-nonsense guide on how to measure your bra size at home

·4-min read

How to measure your bra size is something that seems straightforward, but if you Google it, you can easily fall down a rabbit hole of confusing information. It's something we often do just once (probably a shop bra-fitting back when puberty arrived) and then blissfully ignore for the foreseeable future. But, it's coming at a cost, because research suggests that 90% of British women are actually wearing the wrong bra size, despite the obvious telltale signs.

Signs you're wearing the wrong bra size

If your bra doesn't fit properly, chances are you're not getting the best form of support. Some people even report experiencing discomfort such as:

  • straps slipping off

  • gaping cups

  • spillage

  • underwire digging in

  • tightness around your rib cage

  • back and shoulder pain

Can your bra size change?

Yes, absolutely! Your bra size is always going to vary. Factors including diet, weight loss, and hormone fluctuations all contribute, and you may even be totally different cup sizes depending on the brand you purchase.

But guessing games aside, it is good to have a definitive number and letter to be looking out for to make shopping for a new bra (especially online) enjoyable again.

All you need to measure your bra size at home is a tape measure, and a piece of paper to take notes of each measurement you make.

How to measure your bra size at home

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  1. First up, let's measure your band size. While braless, bring the tape measure around the top of your rib cage, just below where your bra would usually sit. Pull it snug, but not too tight, and take the measurement in inches. Write it down because we'll come back to it in a second.

  2. Whatever number you got as your measurement (e.g. 30), we're going to add another number to that. So, if you got an even number as your measurement, you're going to +4, or if you got an odd number, +5. E.g. if your original measurement was 30, it would be 30 + 4 = 34 (band size). Easy, right?

  3. To measure your cup size, wrap the measuring tape around the fullest part of your chest, and write down the measurement to the nearest whole number.

  4. We hope you like maths! Now subtract your calculated band size from step one (e.g. 34) from the bust measurement you've just done. The difference in inches determines your cup size. E.g. 37 inches (bust) - 34 inches (band) = 3 inches. That's a 34C. Refer to the chart below for a helping hand...

Photo credit: Yeji Kim
Photo credit: Yeji Kim

It's worth noting that there may be occasions where you need to move up or down a bra size, depending on the brand and/or style.

Here's a guide for how to move up and down a band or cup size:

Photo credit: Yeji Kim
Photo credit: Yeji Kim

It may take a few attempts at the cycle of buying, returning, and re-buying in a different size to get this totally right, but once you know, you know.

For example, if you're currently wearing a 36C and it's gaping open at the cups, you may want to try a 36B. However, if you're wearing a 36C and find the underwire is digging into your sides, it may be because you need a 38C.

Signs your bra fits properly

Once you think you're happy with how your bra fits, there are a couple of signs to be sure:

The bra feels secure on the loosest hook. Your bra will lose its elasticity over time, so starting on the hook that gives the biggest band means that you can tighten it when you need to, rather than realising it's too big when it's too late.

Your straps feel fixed in place but don't dig in. There's nothing worse than pulling your bra straps up 100 times a day. Tighten your band first, and then tighten your straps so they're secure, but not hurting.

There is a finger-width of space underneath the band. A good indicator of whether your bra fits you properly is how many fingers you can slide underneath the band. A well-fitted bra should only let you slide one finger under it.

Follow all of these steps and you'll be on your way to some well-deserved, well-cupped boobs. Oh, and a bra that fits properly. If you needed an excuse to hit 'purchase' on that lingerie set that's been sitting in your cart for months...you're welcome.

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