Quick answer
Measure your underbust snug and your full bust at the fullest point while wearing a thin, unlined bra or no bra, then compare those two numbers against each brand's own size chart. Write both numbers down and re-measure once to confirm. Bralette sizing varies by brand, so the chart that ships with the product always beats a generic conversion table.
A bralette has no underwire and no hook-and-eye band, so it has to fit correctly from the first wear. That makes measuring yourself at home worth the ten minutes it takes. You need a soft measuring tape, a mirror, and a thin bra or no bra at all.
This guide walks through the same five steps every time, so your numbers stay consistent whether you are ordering a lace bralette, a bandeau, or a swim top. If you want the broader fit picture first, our bralette sizing guide covers body types; this article focuses on the tape itself.
What you need before you start
A flexible cloth or vinyl tape gives the most accurate read because it follows your ribcage curve. A rigid tape measure or a phone app will flatten the shape and push your number higher or lower than reality. If you only have a rigid tape, use a piece of string and lay it against a ruler afterward.
Wear a thin, unlined bra or nothing at all. A padded or push-up bra adds volume that is not yours, and a sports bra compresses the bust. Stand in front of a mirror so you can see whether the tape is level all the way around.
- Soft tape, string plus ruler, mirror, and a pen and paper
- Thin bra or no bra, and no bulky clothing over the ribcage
Step 1: Measure your underbust
Wrap the tape directly under your bust where the band would sit, keeping it level and snug but not tight. Breathe out normally and read the number at the point where the tape meets itself in front. Round to the nearest whole inch or centimeter and write it down.
The most common mistake is pulling the tape so tight that it digs in. That gives you a smaller number than your body needs, and a bralette band that feels restrictive by the end of the day. The tape should touch your skin without leaving a mark.
- Checkpoint: the tape should sit level at the back, not ride up
Step 2: Measure your full bust
Wrap the tape around the fullest part of your bust, usually across the nipple line, and keep it parallel to the floor. Stand tall with your arms down. Read the number at the front where the tape meets, then write it beside your underbust number.
your arms
Do not pull the tape tight here. You want the tape to rest on the surface of the bust without compressing it. If the tape slopes down at the back, the number will read smaller than your true bust measurement.
- Checkpoint: arms relaxed at your sides, tape parallel to the floor
Step 3: Measure a second time
Repeat both measurements once more and compare. If the two readings differ by more than about half an inch, something moved: the tape tilted, your posture shifted, or you breathed differently. Re-measure until the two sets match closely.
This second pass is what separates a reliable at home bralette sizing routine from a one-off guess. It also helps if you are measuring between sizes, because you will know which number is stable and which one is wobbling.
- Checkpoint: two matching readings before you move on
Step 4: Compare against the brand's own chart
Take your two numbers to the size chart on the product page, not a generic conversion table. Brands cut bralettes differently, and some charts use underbust and bust while others use a simple XS through XL scale. Match the chart's method to the numbers you just took.
If a chart only lists a size range without measurements, treat that as a decision limitation and look for a fit note or model measurement instead. When you are between two sizes, the underbust number usually decides the band, and the bust number decides the cup coverage.
- Checkpoint: your underbust number should fall inside the band range, not at the edge
Step 5: Check the fit signals after it arrives
Once the bralette is on, the band should stay level in back and feel snug without pinching. The center front should lie flat against your sternum, and the straps should not dig into your shoulders or slide off when you raise your arms. If the band rides up, the size is too loose.
A little stretch is normal in lace and mesh styles, but a band that leaves red marks after an hour is too tight. If you are between sizes and the band is the problem, sizing up usually solves it more often than sizing down.
- Checkpoint: band level, center flat, straps staying put
Your five-step measuring routine
- Set up with a soft tape: Use a flexible cloth or vinyl tape and wear a thin, unlined bra or nothing at all. Stand in front of a mirror so you can see the tape stay level. A rigid tape or a padded bra will skew both numbers.
- Measure the underbust snug: Wrap the tape under your bust where the band sits, breathe out, and read the number at the front without pulling tight. If the tape leaves a mark, it is too tight.
- Measure the full bust level: Wrap the tape across the fullest part of the bust with arms down and the tape parallel to the floor. A sloping tape at the back reads smaller than your true bust.
- Repeat both measurements: Take a second full set and compare. Re-measure until the two readings match within about half an inch. Two matching sets beat one fast guess.
- Match to the brand chart: Compare your underbust and bust numbers to the size chart on the product page, not a generic conversion table. If the chart is missing measurements, treat it as a limitation and look for fit notes.
Fit details worth knowing from our catalog
- Layla: Sizing runs XS/S for 32A, 32B, and 34A, and M/L for 34B and 36C. This is a cup-and-band style chart rather than a simple XS to XL scale, so match your measured bust and underbust to those specific letters before ordering.
- rebecca-bikini-fbe721a4a70e0903f0555da1-1494910">Rebecca Bikini: The size chart lists separate top and bottom measurements, with top bust ranging from 33.1 inches at XS to 38.2 inches at L. Because the top and bottom are sized independently, use your full bust measurement for the top and your waist for the bottoms instead of picking one size for both.
- Playing Hard to Get: Sizes run 0XL through 4XL, with waist ranges from 28.3-46.5 inches at 0XL up to 37.8-55.9 inches at 4XL. The waist range is wide at every size, so your underbust and waist numbers matter more than a single letter when you are choosing between two adjacent sizes.
Measure underbust and full bust twice, keep the tape soft and level, and compare against the chart on the product page. That routine takes about ten minutes and gives you a bralette size measurement you can reuse for every order.
