Bra Fitting Guide – How to Measure Your Bra Size at Home
Let’s be honest — most of us think we know our bra size, but that number we got years ago might not be doing us any favours anymore.
Bodies change with time, hormones, and life. What once fit perfectly can suddenly feel like a medieval torture device or a soggy hammock.
But here’s the good bit: getting your bra fit right is easy, private, and totally worth it.
A well-fitted bra lifts more than just your breasts — it lifts your posture, your clothes, and your mood.
You don’t need anyone with a tape measure in a changing room; you can do it at home in five minutes, with a mirror and a bit of curiosity.
So pop the kettle on, grab a tape, and let’s get you perky and proud again.
No fitting-room fuss, no need to fear,
Your perfect fit begins right here.
Step 1 – Find Your Band Size
Here's the correct way to measure:
Wrap your tape snugly around your ribcage, right under your bust — not too tight, not loose enough to slide up your back.
Take a deep breath, exhale, and note the number in inches.
Even number? That’s your band size.
Odd number? Round up to the next even.
That’s the bit that does the work, so if your band’s wrong, everything else is fighting against it.
(NOTE: Some bra fitting guides and calculators will tell you to add four or five inches to your underbust measurement, but this is outdated advice. The "add four" method was popularised by Warners in the 1930s when bra design was in its infancy - it simply doesn't work well with modern bras.)
Step 3: Since everyone's breasts are different in terms of shape (even between your own breasts), the most accurate way to determine your cup size is by using your current bra size as a starting point. If you don't have an existing bra, take a look at the sized cups for your band and give the one that you feel will be the best a try. The cups are sized relative to the band, so if you were to try a smaller band size but keep the same cup size, the cups would be too small - if you go down a band size you need to go up a cup size. If you decide to go up a band size, then to maintain the cup size you will need to go down a cup size.
Step 4: Put the bra on around your body first doing it up on the LOOSEST SETTING. The elastic in the bra will loosen with age, so you'll want to be able to tighten it through it's life and maximise its lifespan. Wiggle your breasts into position, yes wiggle, it works! Tighten the shoulder straps so that they do not dig in and hurt, or slip off the shoulder easily. The band around the body should be taking the main weight of the breasts.
Does the bra feel tight around the body? If so, good! It may feel too tight, but this is because we are used to wearing bras that are too big for us. It should feel tight, but not dig in. You should be able to get 2 fingers side by side between the bra and your skin, and it should have a little bit of give. Check that the weight of the breasts is well supported so the shoulder straps are not digging in at the top. It should of course feel comfortable.
Step 2 – Work Out Your Cup Size
Now measure around the fullest part of your bust (usually across the nipples). Keep the tape level — no sneaky drooping at the back.
Subtract your band size from this new number.
Each inch of difference equals a cup size: one inch = A, two = B, three = C, and so on.
Don’t panic if you land between sizes — bras are like jeans; every brand thinks they know better. Treat this as your starting point.
Step 3 – Does Your Bra Pass the “Happy Boob” Test?
Once your bra is on, there are a few golden rules to check. A quick run-through of these can tell you instantly if you’ve got the right size:
Does it run straight around your body? It mustn’t be pulled up at the back.
Are the bra straps sitting straight on your shoulders? They should support without digging.
Do the underwire or cups follow the natural shape of your breasts? They should start flat against your ribcage and curve smoothly round, tracing your shape.
Lift your arms. Check that the underwire holds all your breast tissue in and sits flat between your breasts.
Check the cup width. It shouldn’t stop short at the side — your breast should sit fully within it, right under your arm.
If the bra pulls away at the front, try a tighter band size to draw it in. (When you go down a band size, go up a cup size — and maybe one more if needed.)
If that new band feels too tight, return to your original band but go up a cup size.
Does the cup sit flush at the top? If it gapes, try a smaller cup; lace bras are the worst offenders for this.
Double-boob alert! If you’ve got humps above the cup, move up a cup size or even two.
Deep shoulder dents? Loosen those straps — the band should do most of the lifting.
Is the band riding up? Try a tighter band size.
Underwire digging in? Swap to a different bra first; if it still happens, go up a band size.
When all those boxes are ticked, your bra should look smooth, feel supportive, and move with you — not against you.
Step 4 – Fine-Tuning
By now you’ll have a clear idea where your fit sits — but bras are as individual as bodies. A few small tweaks can turn a good fit into a perfect one.
If the band feels snug on the loosest hook, that’s ideal; it’ll relax over time. If you’re already on the tightest hook and it still feels loose, go down a band size and up a cup.
If you’re struggling to breathe, do the opposite!
Try on your best-fitting bra and stand side-on in a mirror. The band should stay level, and your bust should sit roughly halfway between your shoulder and elbow — a quick visual cue that you’ve got the lift just right.
A properly fitted bra will:
Keep its shape longer because it isn’t stretched to bits.
Support your breasts so they stay happier and perkier.
Help with posture and back comfort if you’re fuller-busted.
Make every outfit hang better — even a plain T-shirt looks polished.
If you’ve checked all that and still feel unsure, don’t overthink it. Comfort always wins — your body will tell you when the fit is right.
Tips for wearing breast enhancers/chicken fillets
Now when wearing breast enhancers, the small styles can often slip into your existing bra with no problem. You may need to tighten the straps to give the cups more support with the extra weight.
With the large enhancers you will need to go up at least a cup size to accommodate the extra breast. This depends on your original size. E.g. if you are an AA cup and you buy the biggest enhancer then chances are it won't fit in your bra.
The best thing to do is to buy the enhancer first then take them with you to a bra shop so you can try on bras that work best with your extra size. Remember to follow the tips above, treating the enhancer as it if was part of you.
If you've followed the guide to accurately measuring your bra size, you should be feeling pretty amazing right now. Stand back and marvel at your new found breasts, before sauntering off to show the world! NOTE: whilst I'm a huge advocate of 'sharing is caring', indecent exposure is a thing and I accept no responsibility for your future criminal records, hehe.
If you need any advice about any of my breast enhancers, please get in touch and I will be happy to help.
Jo