How to Measure Your Bra Size at Home for a Better Fit

Quick answer

To measure your bra size at home, wear an unpadded bra, wrap a soft tape snugly around your ribcage just under your bust for the underband, then measure around the fullest part of your bust. Subtract the underband from the bust to find your cup size. For D+ sizing, always round the underband to the nearest even number and double-check that the tape stays level all the way around.

Before you start: what you need and how to prepare

You only need a soft measuring tape and a mirror. Wear an unpadded or lightly lined bra—not a push-up or sports bra—so the tape follows your natural shape. Stand in front of a mirror so you can see if the tape twists at the back. If you are between sizes or have a D+ cup, take each measurement twice; a half-inch difference can change your cup letter.

For the most accurate underband, exhale normally and let the tape sit snug against your ribcage. It should not dig in or slide down. If you have a fuller bust, ask someone to help hold the tape level at the back, or use a mirror to check. A common mistake is measuring over a padded bra—this adds volume and gives a false bust measurement.

Measure your underband (ribcage)

Wrap the tape around your ribcage, directly under your bust, keeping it parallel to the floor. Pull it snug—snug enough that it stays in place when you breathe out, but not tight enough to leave marks. Round the number to the nearest whole inch. If the result is an odd number, round down to the nearest even number to get your underband size (for example, 33 inches becomes 32).

For D+ sizes, a common mistake is measuring too high on the ribcage, which makes the band feel tighter than it is. Check the tape is sitting on your ribcage, not on breast tissue. Write down this number; you will use it for both the band size and the cup calculation.

Measure your bust at the fullest point

Wrap the tape around the fullest part of your bust, usually across the nipple line. Keep the tape level and relaxed—do not pull it tight or let it compress your bust. Stand straight with your arms down. If your bust is full on the sides, make sure the tape covers the fullest projection, not just the front.

A frequent mistake is letting the tape dip at the back, which reduces the bust measurement. Use a mirror to check the tape is straight across your back. Record the number to the nearest whole inch. If you are between inches, round up for the bust measurement to avoid a too-small cup.

Calculate your cup size

Subtract your underband measurement from your bust measurement. The difference in inches determines your cup letter. A 1-inch difference is an A cup, 2 inches is a B, 3 inches is a C, 4 inches is a D, 5 inches is a DD, 6 inches is an E (or DDD in some US brands), 7 inches is an F, and so on. For example, a 32 underband and 38 bust gives a 6-inch difference, which is a 32E.

D+ cups start at a 4-inch difference (D) and go up. If your calculation gives an odd number, round the underband down and the bust up to keep the cup from being too small. Remember that cup size is not static—it changes with the band. A 34D has a different cup volume than a 32D.

Check the fit and adjust

Once you have your size, try a bra in that size and check the band first. The band should provide most of the support and stay level all the way around. You should be able to fit two fingers under the band at the back. If the band rides up, go down a band size and up a cup size (for example, from 34D to 32DD). If the band digs in, go up a band size and down a cup size.

Next, check the cups. The center gore should sit flat against your sternum, and the underwire should encircle your breast tissue without poking. If you spill over the top, go up a cup size. If the cups wrinkle, go down a cup size. For D+ sizes, small adjustments make a big difference. Our Curvy Kate size guide can help you convert your measurements to specific styles.

Step-by-step bra measuring guide

1. Step 1: Prepare your tape and bra: Wear an unpadded bra and stand in front of a mirror. Hold the tape so it is not twisted. Checkpoint: the tape should lie flat against your skin without compressing it.
2. Step 2: Measure your underband: Wrap the tape snugly around your ribcage under your bust, keeping it level. Round down to the nearest even number. Common mistake: measuring too high or too loose—this makes the band feel tighter than it is.
3. Step 3: Measure your bust: Wrap the tape around the fullest part of your bust, keeping it level and relaxed. Round up to the nearest whole inch. Checkpoint: the tape should not dip at the back; use a mirror to confirm.
4. Step 4: Calculate your cup size: Subtract the underband from the bust. Each inch of difference equals one cup letter (1=A, 2=B, 3=C, 4=D, 5=DD, 6=E, etc.). Common mistake: using an odd underband number—always round down to the nearest even number.
5. Step 5: Try a bra and adjust: Test the band and cups. If the band rides up, go down a band and up a cup. If it digs in, go up a band and down a cup. Next step: use these measurements to shop D+ styles, and re-measure every six months or after any body changes.

Product facts to keep in mind

• Curvy Kate Spellbound Balcony Bra White: Curvy Kate Spellbound Balcony Bra White: balcony cups for everyday shape and support; floral lace top cup; underwired, non-padded cups; fully adjustable straps (32-36 D-F). A balcony bra like this works well for D+ sizes because the non-padded cups and adjustable straps let you fine-tune the fit you measured.
• Curvy Kate All Night Lace Tanga Black/Blush: Curvy Kate All Night Lace Tanga Black/Blush: main fabric 85% Polyamide, 15% Elastane; gusset lining 100% Cotton. The stretch polyamide blend gives a flexible fit, and the cotton gusset adds breathability—useful when you are checking how a full set feels after measuring.