Bra Fitting for Trans Women: Measurements and Sizes

Finding a bra that actually fits took me years. Not because the information isn't out there, but because most of it is written for cis women's bodies, and a trans woman's body has some genuinely different proportions to account for. I've ended up with bras that dug in on the sides, bands that rode up constantly, straps that fell off my shoulders no matter how I adjusted them. All of that is fixable once you understand what's actually going on.

I'm Robyn Electra, founder of Gaff and Go. I've been through the trial and error so you don't have to do. This is what I know about bra fitting for trans women.

WHY BRA FITTING IS DIFFERENT FOR TRANS WOMEN

The main difference comes down to the ribcage. People assigned male at birth tend to have a wider ribcage and a broader sternum, which means the breasts sit wider on the chest than they would on a cis woman of the same cup volume. Most bras are designed for a narrower chest, so the standard size charts don't always translate directly.

This creates a specific problem: if you go by volume alone and buy the cup size that matches how much breast tissue you have, the bra will often be too narrow. The underwire or the base of the cup will dig into the sides of your breast tissue rather than sitting flat against your chest wall.

The fix is not complicated once you understand it, but it does mean sizing differently than you might expect.

HOW TO MEASURE YOURSELF

You need two measurements: your band size and your bust measurement.

For your band size, measure around your ribcage right at the base of your breasts. Keep the tape snug but not tight. Take that number in inches and round to the nearest whole number. If that number is even, add four inches. If it is odd, add five. That gives you your band size. So a 30 inch measurement rounds to 30, plus four gives you a 34 band.

For your bust measurement, measure around the fullest part of your chest, usually just below the nipple line. The difference between your bust measurement and your band size determines your cup size: no difference is AA, one inch is A, two inches is B, three inches is C, four inches is D, five inches is DD, and so on.

One useful trick is sister sizing. Bra sizing works on a sliding scale, so if you need a 36B but the fit isn't quite right, a 34C has the same cup volume in a slightly smaller band. You can move up or down a cup size alongside the corresponding band adjustment. This is helpful if you are between sizes or if a particular brand runs slightly different.

THE WIDER CUP RULE

Here is the thing that trips up a lot of trans women when they are first finding their size. Because breast tissue is still developing, or because you simply do not have a lot of volume yet, you might assume you need a small cup. A or B, maybe. But because of the wider ribcage and the broader spacing of the breasts, a small cup on a larger band will often be too narrow to wrap around your chest properly.

The cup size tells you about volume, but it also determines the width of the bra at the front. A wider cup gives the underwire or base more room to sit flat across your chest rather than cutting into the sides.

What this means in practice: go up a cup size from what you think you need. You might end up in a 36C when you thought you were a 36A. There may be some space in the cup, and that is fine. The bra will still support you, it will sit comfortably, and as your body develops further on HRT it will fill out more. A bra that is slightly too big in the cup looks and feels much better than one that is cutting into the side of your breast tissue.

START WITH A BRALETTE, NOT AN UNDERWIRE

This is advice I wish someone had given me earlier. If you are earlier in your transition and still developing breast tissue, underwire bras are going to cause you problems.

Underwire bras require a certain amount of breast density and volume in order to sit correctly. Without it, the wire has nothing to tack against and it will shift, dig in, or float away from your body entirely.

Start with bralettes or wireless bras that have some cup shaping to them. The key word there is shaping. A strict compression fit, like a sports bra that pushes everything flat, is not what you want. You want something with a cup that encourages the breast tissue to sit forward rather than pressing it back and outward.

Our lace bras and bralettes are designed for trans bodies and have exactly this kind of shaped cup. They are soft, comfortable, and work well at all stages of transition. The band needs proper tension: you should be able to pull it about an inch away from your body. If you can slingshot it, it is too loose and it will walk up your back.

Once you have more volume and density, underwire becomes more workable. But I still wear wireless bras most of the time. They are more comfortable, and for trans women specifically, the wider chest means many standard underwires will still be slightly too narrow anyway.

SPORTS BRAS: WHAT TO LOOK FOR

Sports bras are great for everyday wear and not just the gym. The important thing is to avoid anything with harsh compression: you do not want your breast tissue pushed back under your arms, you want it sitting forward.

Our trans sports bras are designed with this in mind. They are supportive without flattening, breathable, and built for trans bodies rather than adapted from a standard compression cut. Racer back styles are particularly good if you find that regular straps fall off your shoulders, which is a common issue with broader or more rounded shoulder frames.

Sports bras with built-in padding also give you more volume if you are earlier in your transition, which is worth knowing about.

THE STRAP LENGTH PROBLEM

Broader shoulders and a longer back mean that strap length matters more for trans women than most bra advice acknowledges. If the straps are too short, they pull the back of the bra upward, the band rides up, and you spend the whole day hauling everything back down. Straps that fall off constantly are usually a sign that they need lengthening rather than tightening.

What you want is for the back of the bra to sit low and level with the front, at the base of the breast. If you cannot get it there because the straps run out of length, try a different brand or look for a tailor who can lengthen them. It is a simple alteration.

Balcony-style bras, which have straps set wider on the shoulders, can be a good option if you have broader square shoulders. They sit beautifully on a wider frame.

ADDING VOLUME: BREAST PADS AND BREAST FORMS

If you want more volume than your current breast tissue provides, you have options at different price points.

Breast pads are the simplest starting point. They are lightweight removable inserts that sit inside the cup of your bra. Many of our bralettes and sports bras have built-in pockets for them, and our one-piece tucking swimsuits come with removable luxury breast pads included. They are also easy to swap between different bras, so one pair of pads can work across your whole wardrobe.

Breast forms are the next step up. They are heavier, more realistic, and give more substantial shape. The weight is also useful: a common problem with bras that do not have enough weight in the cup is that they migrate upward and sit uncomfortably under the arms. A properly weighted cup stays put.

If you are using any kind of form or prosthetic, look for bras with pockets inside the cup to keep them in place. This matters most with wireless bras, where there is no wire to hold things forward.

BUILDING YOUR BRA WARDROBE

You do not need a lot to start. Three bras covers most situations: a wireless everyday bra or bralette, a sports bra for active days and casual wear, and a more structured or padded option for going out. Black and white cover most bases in terms of what shows under clothing.

Our bras and bralettes collection covers all of this in one place: lace bras, sports bras, bikini bras, and bralettes, all designed for trans bodies, available in a wide range of colors from black and nude through to red, purple, orange, and pink. Multi-pair bundles are available if you want to build your wardrobe in one go.

When you find a bra that fits, buy one first and wear it for a week before buying more. A bra that feels right immediately can reveal problems after a full day of wear. Try before you commit to a full set.

WHERE TO START

If you are not sure where to begin, start with our bras and bralettes and add breast pads if you want volume. If you have questions about sizing, our FAQs cover the most common ones, and you can always get in touch directly.

Finding the right bra takes some trial and error. But once you understand how trans bodies fit differently, the process gets a lot more straightforward.