How to measure your bra size at home

A shocking number of us are wearing the wrong size, and it's almost never our fault — it's that nobody ever showed us the two-minute method. So here it is. This is how to measure your bra size at home with a soft tape measure, a mirror, and zero guesswork. No appointment, no fluorescent fitting room, no stranger with a tape.

We'll also be honest about something most guides skip: our current size range is narrow, so at the end we'll show you how to use sister sizing to find your best fit within it.

What you'll need

• A soft fabric tape measure (the floppy kind for sewing). If you only have a rigid one, a piece of string plus a ruler works in a pinch.
• A non-padded, unlined bra — or no bra at all. A padded bra adds inches and throws the cup math off.
• A mirror, so you can keep the tape level all the way around.

Measure in front of the mirror, keep the tape snug but not strangling, and keep it parallel to the floor. A tilted tape is the number-one source of a wrong reading.

Step 1: Measure your band

Your band size is the foundation — it does most of the support work, so this is the number to get right.

1. Wrap the tape around your ribcage, directly under your bust, where the band of a bra sits.
2. Pull it snug and level — firm, like a slightly tight hug, because the band is meant to be supportive.
3. Read the number in inches. If you land on an odd number, round to the nearest even number.

That even number is roughly your band size. (Brands vary by an inch or two, which is normal — we'll use this as your anchor.)

Step 2: Measure your cup

Cup size is the difference between your bust and your band, not a fixed measurement.

1. Wrap the tape around the fullest part of your bust — usually right across the nipple line.
2. Keep it loose and level: this measurement should be relaxed, not snug. Don't compress.
3. Subtract your band number (step 1) from this bust number.

Each inch of difference is roughly one cup size:

• 1 inch → A
• 2 inches → B
• 3 inches → C
• 4 inches → D

So a 34-inch band and a 36-inch bust is a 2-inch difference — a 34B.

Common mistakes (that fake your numbers)

• Measuring over a padded bra. Adds volume, inflates the cup, ruins the math. Go unlined or bare.
• A loose band measurement. A floppy band number gives you a too-big band, which then makes you over-tighten the straps and blame your shoulders. Snug the band.
• A tight bust measurement. Squeezing the tape across the bust shrinks your cup result. Keep that pass relaxed.
• A tilted tape. Higher in the back than the front is incredibly common and adds phantom inches. Mirror check, every time.
• Measuring once. Take each measurement two or three times and trust the number that keeps repeating.

Sister sizing: the trick that widens your options

Here's the concept that quietly fixes a lot of "they don't make my size" problems. Sister sizes are the bra sizes that share the same cup volume — when you go up a band, you go down a cup, and vice versa, and the cup stays roughly the same actual size.

For example, these three hold a similar cup volume:

• 34C → up a band, down a cup → 36B
• 34C → down a band, up a cup → 32D

So if your "true" size isn't available, your sister size often fits beautifully — you're just trading a bit of band snugness for the same cup. Going up a band makes it looser around the ribcage; going down a band makes it firmer.

Our honest size range right now

We'll be straight with you: Bijou currently makes the base bra in 32B, 34B, 34C, and 36C, in nude and black. That's a deliberately tight starter range while we're getting going, and it won't fit everyone — we'd rather say that plainly than pretend.

Use your measurement plus sister sizing to see if you land in our range:

• Measured a 34A? Your sister size 32B is one we make.
• Measured a 32C or 36B? Sister-size toward 34B/34C.
• Right on 34B, 34C, or 36C? You're squarely in our wheelhouse.

If you're nowhere near these, hold tight — expanding the range is on the list, and the best way to nudge it up the priority list is to tell us your size on the waitlist.

Why fit matters more with our system

Because our clip-on straps are styling, not structure, the base bra's fit is doing all the support work. A great band-and-cup fit is what makes the whole thing comfortable — we get into that in are interchangeable straps actually comfortable?. Nail the size and the fun part (swapping pretty straps) gets to be purely fun.

Frequently asked questions

How often should I re-measure? Any time your weight shifts noticeably, after pregnancy, or roughly once a year. Bodies change; tape doesn't lie.

My band and cup point to different sizes on different brands — why? Sizing isn't perfectly standardized across brands, which is exactly why sister sizing exists. Treat your measurement as a strong starting point, not gospel.

What if I'm between two cup sizes? If your difference lands on a half-inch, try the larger cup first — a slightly roomy cup is far comfier than one that cuts in.

Ready when you are

Once you know your number, you know your base bra — and from there it's all straps. We're prelaunch for now, so join the waitlist (tell us your size!) and preview the collection while you wait.