How to Measure Bra Size at Home: A Bra Fitting Guide
How to measure bra size at home takes a soft tape, a mirror and about five minutes. You measure under your bust for the band, around the fullest part for the bust, and the gap between the two gives you the cup.
Most of the women we fit in our lingerie department come in wearing a band that is too loose and a cup that is too small. It is the most common fitting problem we see. It is also the easiest one to put right.
At a glance
- Your band is the snug measurement under your bust, rounded up to an even number
- Each inch between your band and your bust is one cup size
- Sister sizes keep the same cup volume on a different band
- The band should do most of the work, not the straps
- Bra fitting in our Shaftesbury shop is free and needs no booking
- How to measure your bra size
- UK bra size chart
- Sister sizes
- How a bra should fit
- If one breast is larger than the other
- Choosing a style
- Frequently asked questions
How to measure your bra size
Wear a non-padded bra, or none at all, so moulding and padding do not throw the numbers out. Stand straight in front of a mirror so you can see the tape at the back.
1. Measure your band
Wrap the tape snugly around your ribcage, directly under your bust. Check it sits level all the way round, then breathe out and read it in inches. Round to the nearest whole inch. An odd number goes up to the next even one, so 31 inches becomes a 32 band.
2. Measure your bust
Now take the tape around the fullest part of your bust. Keep it level across your back and hold it loosely. Pull it tight and you will come out a cup size short.
3. Work out your cup
Take your band away from your bust measurement. Each inch of difference is one cup size on the UK scale, using the chart below. A 34 inch band with a 40 inch bust is six inches apart, which makes you a 34E.
UK bra size chart
UK cup sizes double up from D onwards, which is where most of the confusion comes from. Here is the full run we fit to.
| Bust minus band | UK cup | Bust minus band | UK cup |
|---|---|---|---|
| 1 inch | A | 9 inches | G |
| 2 inches | B | 10 inches | GG |
| 3 inches | C | 11 inches | H |
| 4 inches | D | 12 inches | HH |
| 5 inches | DD | 13 inches | J |
| 6 inches | E | 14 inches | JJ |
| 7 inches | F | 15 inches | K |
| 8 inches | FF |
Some of the brands we stock label in European sizes as well. The band converts in steps of five:
| UK band | 30 | 32 | 34 | 36 | 38 | 40 | 42 | 44 |
|---|---|---|---|---|---|---|---|---|
| EU band | 65 | 70 | 75 | 80 | 85 | 90 | 95 | 100 |
Cup letters stop lining up once you pass a D, so check the brand's own chart for those. Treat your tape measure result as a starting point too. A 34E in one label can feel quite different in another, which is why we always bring two or three to try.
Sister sizes
Go up a band and down a cup and the cup holds the same volume. These are called sister sizes. They are the answer when a cup fits well but the band feels wrong.
| Smaller band | Starting size | Larger band | ||
|---|---|---|---|---|
| 30FF | 32F | 34E | 36DD | 38D |
| 30G | 32FF | 34F | 36E | 38DD |
| 30E | 32DD | 34D | 36C | 38B |
If your band rides up your back, go one band down and one cup up. A 34E that keeps creeping up usually fits far better as a 32F.
How a bra should fit
Before you judge anything, do the swoop and scoop. Lean forward, sweep the breast tissue from under your arm into the cup with your other hand, then stand up straight. Then check these in the mirror, front and side on.
- The band sits level all the way round, firm enough that two fingers just slide underneath
- On a new bra, use the loosest hook so you can tighten it as the elastic gives
- The centre panel lies flat against your breastbone
- The cups are smooth, with no spilling over the top and no wrinkles
- Underwires rest on your ribcage behind the breast tissue, never on it
- Straps stay up without digging in
Sore shoulders are a band problem. If the straps are carrying the weight, the band is too big. Most of the support should come from the band.
If one breast is larger than the other
Nearly everyone is a little uneven, so this is perfectly normal. Fit the cup to the larger side, then shorten the strap on the smaller side so that cup sits close. A cup with a stretch lace top edge copes well with the difference. So does a removable pad, worn on the smaller side.
After breast surgery the difference can be much bigger. We take real time over post-surgery fittings. Our mastectomy bras have soft pockets that hold a breast form securely.
Your size changes more often than people expect, too. Measure again after any change in weight, during and after pregnancy, through the menopause, or when you take up a new sport. Otherwise once a year is about right.
Choosing a style
Size gets you close. Style decides how a bra feels by four in the afternoon.
- Full cup bras cover the whole breast and are where most fuller cup sizes begin
- Side support bras have an extra panel that brings the bust forward and eases the straps
- T-shirt bras give a smooth line under a fitted top
- Non-wired bras still support properly if wires have never agreed with you
Every brand cuts a little differently, so if you are unsure how one comes up, ask us. That is what we are here for.
Come in and we will fit you properly. It is free and you do not need to book. Our fitters are fully trained and have been doing this here for years, and Shirley still does a fitting herself when she can. We are at 30 High Street, Shaftesbury, Monday to Saturday from 9.30am to 5pm, on 01747 852444.
Frequently asked questions
How do I measure my bra size at home?
You need a soft tape measure and a mirror. Measure snugly around your ribcage, directly under your bust, and round up to an even number for your band. Then measure loosely around the fullest part of your bust, keeping the tape level. Take the band away from the bust: each inch of difference is one cup size, so a six inch gap on a 34 band is a 34E. Treat it as a starting point and try a size either side.
How do you measure cup size for a bra?
Cup size comes from the difference between your bust and your band measurement. One inch is an A, two a B, three a C and four a D. After that the UK scale doubles up, so five is DD, six E, seven F and eight FF, running on to K at fifteen inches. The cup only means something next to its band, which is why a 32F and a 36DD hold the same volume.
What are sister sizes in bras?
Sister sizes are bra sizes with the same cup volume on a different band. Going up one band means going down one cup, so 34E, 36DD and 38D all hold the same amount, and so do 32F and 30FF. They help when a cup fits well but the band is too loose or too tight. If your band rides up your back, try one band smaller and one cup larger.
How do I know if my bra fits properly?
The band sits level and firm on the loosest hook, with room for two fingers underneath. The centre panel lies flat on your breastbone, the cups are smooth with no spilling or wrinkling, and underwires sit behind the breast tissue. The straps should stay up without digging in. If your shoulders ache or the band rides up at the back, the band is too big.
What should I do if one breast is bigger than the other?
Fit the bra to the larger breast, then shorten the strap on the smaller side so that cup sits close. A cup with a stretch lace top edge adapts well, and a removable pad on the smaller side evens things out. After breast surgery the difference can be greater, and a post-surgery fitting with a pocketed bra is worth the time.
Do I need to book a bra fitting in Shaftesbury?
No. Bra fitting at our shop is free and you do not need an appointment. Come into 30 High Street, Shaftesbury, any time we are open, Monday to Saturday from 9.30am to 5pm. Our fitters are fully trained, and Shirley still does fittings herself when she can. If you would like to check we have your size first, ring us on 01747 852444.
Written by Shirley Allum
Shirley has run her Shaftesbury boutique since 1997 and still does all the buying herself, across fashion, footwear and lingerie. She and her team have been dressing the women of Dorset for nearly thirty years.
