How to find your wireless bra size (measurement guide)
If you've made it this far, it's because you're thinking about ditching underwire bras, or you've already done it and don't know what size to order. It's the question we get most in our inbox, and there's a simple explanation: a wireless bra isn't sized the same way as an underwire bra.
In this guide, we'll show you how to measure yourself at home with a tape measure, how to switch from your usual size to sizes S–2XL, and how to tell if you've got the right fit as soon as you put it on.
Two measurements and a tape measure: that's all you need.
The starting point
Why your usual size won't work right away
An underwire bra holds you in by pushing up from below. The underwire is a rigid structure that has to fit exactly into the crease under your bust: if it's too wide, it shifts; if it's too narrow, it digs in. That's why underwire sizing is so specific, and that's why a 90B and a 90C aren't interchangeable.
A wireless bra works differently: the molded cup adapts to your bust and the wide band distributes the weight. Since there's no rigid piece that has to fit in an exact spot, the sizing accommodates variations much better. That's why it's grouped into S, M, L, XL, and 2XL instead of dozens of combinations.
If you're still deciding between the two styles, we compare them here point by point.
This has a practical consequence worth knowing: if your body changes throughout the month, or if you've gained or lost some weight, a wireless bra will continue to fit you for much longer than an underwire bra.
Two minutes in front of the mirror
What you need to measure yourself
- A flexible tape measure, like a sewing tape measure. If you don't have one, a piece of string will do—just measure it with a ruler afterward.
- A mirror, to check that the tape measure is straight.
- Measure yourself without a bra or with a thin, unpadded one. Never measure over a push-up bra, as it will distort the measurement.
Step by step
Where to place the tape measure
There are two measurements, and the order doesn't matter. What does matter is that both are parallel to the floor, all the way around your back.
Underbust measurement
Wrap the tape measure just under your bust, over your ribs, along the line where the bra band would rest. Adjust it so it's snug but not tight: you should be able to slide it slightly. Take the measurement after you've finished exhaling.
Bust measurement
Now measure around the fullest part of your bust, usually at nipple level, with your arms relaxed at your sides. Here, don't pull tight: the tape measure should rest against you, not compress you. If you pull it tight, you'll end up with a cup size smaller than you need.
The charts
From your measurements to your size
If you'd rather not do the math, we have a size calculator: enter your two measurements and it will tell you directly which size to order. The same calculation is explained step by step below, in case you want to understand how it works.
Step 1: from centimeters to the number
The number of your size (85, 90, 95...) comes from your underbust measurement. This is the standard European sizing equivalent, used by most brands in Spain:
| Underbust measurement | Your number |
|---|---|
| 63 – 67 cm | 75 |
| 68 – 72 cm | 80 |
| 73 – 77 cm | 85 |
| 78 – 82 cm | 90 |
| 83 – 87 cm | 95 |
| 88 – 92 cm | 100 |
| 93 – 97 cm | 105 |
| 98 – 102 cm | 110 |
Step 2: from the difference to the cup size
The difference between the two measurements determines the letter:
| Difference between the two measurements | Your cup size |
|---|---|
| 12 – 13 cm | A |
| 14 – 15 cm | B |
| 16 – 17 cm | C |
| 18 – 20 cm | D |
| More than 20 cm | E or larger |
A complete example. Underbust measurement: 80 cm, which in the first chart is a 90. Bust measurement: 96 cm. The difference is 16 cm, which in the second chart is a C cup. Size: 90C.
Step 3: equivalents with Shapeher sizes
Once you have your usual size, all you have to do is find it here. Following the example, a 90C is an M.
| Size | Compatible EU sizes |
|---|---|
| S | 85B · 85C · 85D · 90A |
| M | 90B · 90C · 90D · 95A |
| L | 95C · 95D · 100A · 100B |
| XL | 100C · 100D · 105D · 95E |
| 2XL | 105C · 105D · 110B · 110E |
Two warnings, because we'd rather tell you here than have you return it. The centimeter chart is the European standard, not our own measurement: every brand has its own fit, and there can be up to a size difference. And the equivalents for S, M, L, XL, and 2XL are approximate.
If your size isn't on the list, choose the closest one. And if you're unsure or none of them seem right, write to us with your two measurements in centimeters and we'll tell you which one to order. It takes us less time to do that than to process an exchange.
The ultimate test
How to tell if you've got the right fit
“Not having underwire and having good support is well worth it.”Nira Ser · verified Trustpilot review
Three checks that will tell you in thirty seconds, in front of the mirror.
The two-finger test
You should be able to fit two fingers between the band and your back, with some resistance. If your whole hand fits, it's too big. If you can't fit even one finger, it's too small.
The band, straight
Look at yourself from behind. The band should be parallel to the floor. If it rides up toward your shoulder blades, it's pulling: it's too small, even if it looks fine in the front.
The cup, smooth
No wrinkles and no spilling out over the top or sides. If there's extra fabric, try a smaller size. If you're spilling out, try a larger one.
The second point matters more than it seems: most of the support comes from the band, not the straps. When the band doesn't do its job, you end up compensating by tightening the straps. That's where shoulder marks come from.
Wide band and wide straps: that's where the support comes from, not the underwire.
What's usually done wrong
The four most common mistakes
- Measuring over a padded bra. It distorts both measurements and almost always leads to ordering a size too large.
- Pulling the tape measure tight around your bust. Compressing while measuring gives you a cup size smaller than your actual size.
- Relying only on the label of your current bra. That's the size you bought, not necessarily the one you need. Many women have been wearing a band that's too large for years, compensating with the straps.
- Never measuring again. Your measurements change with weight, pregnancy, and age. If it's been more than a year since you last measured, do it—and if you're over 50, there are specific changes worth knowing.
The age-old question
What if you're between two sizes?
We have a clear recommendation here: choose the smaller size. In a wireless bra, support comes from the band and cup fitting snugly, and one size too large will loosen exactly where you need it firm.
It's much easier to enlarge a band than to fix a cup that's too big. If you notice over time that the band is too tight, an extender will give you a few more centimeters of circumference without affecting the cup. They come in a pack of four and work with any bra, including the ones you already have in your drawer.
And remember: if in doubt, send an email to info@shape-her.shop with your two measurements, and we'll tell you which one to order that same day.
Now all that's left is to choose
Twelve colors, five sizes
Once you have your size, all that's left is to choose a color. These are the solid colors:
Common questions
Frequently asked questions
Does it really hold me in if I have a large bust?
Yes, as long as the band is wide and fits well. The support doesn't come from the underwire: it comes from the band distributing the weight and the molded cup holding you in. What does change is the shape: a wireless bra gives a more natural and less projected silhouette than an underwire bra.
Does it show under clothes?
It shouldn't, if it has no seams or lace on the cup. Lines under a thin t-shirt almost always come from the fabric's seams, not from wearing a bra. Here are the details of what shows and what doesn't.
Can I sleep in it?
Since it doesn't have an underwire, there's no rigid piece that can dig in when you lie down, so many customers also use it for sleeping. If you're between two sizes, the general rule still applies: choose the smaller one.
How often should I replace it?
It depends on use and washing. What shortens the life of a bra the most is the washing machine without protection: the drum distorts the cups. Washing it by hand or in a mesh bag greatly extends its life.
A mesh bag prevents the drum from distorting the cups.
To finish
In summary
Measure your underbust and bust measurements. The first gives you the number, the difference between the two gives you the cup size, and with that you find your size in the equivalence chart—or do it all at once in the calculator. When you put it on, check three things: two fingers in the band, band parallel to the floor, and smooth cup.
If you also notice that it digs in under your bust, then you have the complete diagnosis.
And if you make a mistake, it's no big deal either: you have 30 days to return it if you haven't used it.
