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

Let's be real, who hasn't Googled "how to measure bra size" more times than you can count over the years? It's something that seems relatively straightforward (after all, you only need a tape measure), but you can easily fall down a rabbit hole of confusing information online.

Chances are, your mum dragged you along to an awkward shop bra-fitting at the first signs of puberty in what can only be described as a rite of passage into womanhood. And if you're anything like us, you either haven't been back since or if you did – have been blissfully ignoring the advice from the old dear who measured you.

Well, we hate to break it to you but it's coming at a cost. Research suggests that 90% (!!) of British women are actually wearing the wrong bra size despite the obvious telltale signs. From back pain to just plain discomfort, it really ain't worth it. So let's *finally* establish once and for all how to correctly measure your bra size at home. Trust us, your boobs will thank you.

What are the signs you're wearing the wrong bra size?

If your bra doesn't fit properly, that means you're more than likely not getting the best form of support. You might also experience discomfort such as:

  • straps slipping off or digging in

  • gaping cups

  • breast spillage

  • underwire digging in

  • tightness around your rib cage

  • back and shoulder pain

  • painful red indentations from your straps

Can your bra size change?

Believe it or not, your bra size can change almost monthly. Yep, thanks to factors including your menstrual cycle, pregnancy, and hormone fluctuations, your bra size may often vary while weight gain or loss can also contribute to differing sizes. Plus, you may even be a totally different cup or band size in different brands, just like how clothing sizes aren't uniform across the high street. Helpful, right?

Even more reason why it's worth measuring your bra size each time you shop for a new bra. Matching your definitive number and letter to a brand's size guide will make shopping online in particular not a total guessing game. If you can go in-store to get professionally measured at a speciality retailer like M&S or Victoria's Secret, that's one way to do it. But if you're pressed for time, or simply don't fancy a stranger getting that up close and personal, we've got some handy at-home measuring instructions right here.

All you need to figure out your bra size at home is a tape measure and a piece of paper (or your Notes app) to jot down your measurements as you go.

How to measure your bra size at home with a tape measure

how to measure bra size with a tape measure

First up, measure your band size. The band of your bra should sit directly underneath your boobs. Depending on what style you end up purchasing, the thickness will vary based on how many rows of hooks are on the strap.

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.

how to measure bra size with a tape measure

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 and that's your band size. Easy, right?

how to measure bra size with a tape measure

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. Again, we're working in inches here.

how to measure bra size with a tape measure

We hope you like maths! Now subtract your calculated band size from step two (e.g. 34) from the bust measurement you've just done. For arguments sake, let's say your cup measurement was 37 inches.

The difference in inches equates to its respective letter of the alphabet which determines your cup size. E.g. 37 inches (bust) - 34 inches (band) = 3 inches. C is the third letter of the alphabet, so your bra size translates to a 34C.

If you're still confused, check out our helpful video on how to measure your bra size from our Style Labs:

And, if all that *still* sounds too complicated, why not check out Nudea's Fit Tape? It makes measuring your bra size at home *so* much easier, no complicated adding or subtracting required. And the best part, with every purchase you get a complimentary Virtual Fitting from Nudea to learn how to properly use the bespoke tape from one of the brand's bra experts.

How do bra sizes work?

It might be worth clarifying at this point that if your band size changes, your cup size will change too – and vice versa. This is because the cup volume adjusts with the band size. Sure, your band size is a direct translation of your underbust measurement, but your cup size is worked out in relation to that and in simplified terms, is the volume of your bust to the size of your torso. Even though someone who is a 30C and someone who is a 36C both wear the same cup size, they have noticeably different bust sizes.

What is a bra sister size?

There may be occasions where you need to move up or down a bra size, depending on the brand and/or style. This is called sister sizing. While everyone has a true size, sometimes a bra in that size doesn't fit as well or as comfortably as you might like. Opting for an alternative bra size where the cup volume stays the same is a great solution.

If you're wondering how to move up and down cup sizes, it's pretty simple. If you move up 2 inches on the band (e.g. 36 to a 38), go down a cup size (D cup to a C cup). Conversely, if you want to go down a band size (e.g. 32 to a 30), go up a cup size (AA cup to a A cup). Most bra fitters recommend sizing one up or one down, any more than that and the proportions of the bra will have changed so much it will no longer reflect your true size.

How to measure your bra size without a measuring tape

Don't worry, if you don't have a tape measure to hand, all hope is not lost. Simply find a piece of string, ribbon, or maybe even your dressing gown belt that will wrap around your body. Repeat the steps above, but make sure to mark on your measuring device at what point the ends meet.

Then, simply lay it flat and measure the distance with a ruler or hard tape measure to find out your bust and underbust measurements.

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. This lengthens the lifespan of your bras, which is helpful if you've invested in them.

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. Your band should not be riding up in the back; it should be level all the way around your ribcage for the best support.

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 be snug, and only let you slide one finger under it.

It's a good idea to measure yourself (or get it done in-store) every so often, as our bodies will naturally fluctuate some over the years.

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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