gg-test | la Vie en Rose

Does your bra never feel right? Maybe the straps keep slipping, the band rides up, or you’re just never fully comfortable. If so, you’re far from alone.
A study published on PubMed, the NIH’s medical research database, found that 80% of women wear the wrong bra size. And honestly, it’s no surprise. Bra sizing is anything but intuitive.

With sizing systems that vary from one country to another, cup shapes that change by style, and cuts that differ across brands, it’s easy to feel confused and end up in a size that doesn’t fit.

That’s why our bra experts created this guide. Inside, you’ll find a three-step measuring method, and expert tips to help you spot the signs of a poor fit and how to correct them.

Because a well-fitted bra isn’t a luxury, it’s the foundation.

How to Measure Your Bra Size?

According to our expert, Bianca Izzo, Vice President of Design and Creative Strategy, your ideal bra size depends on two things: taking the right measurements and understanding how to interpret the results. The number represents the band size, while the letter indicates the cup and its corresponding breast volume. Both measurements are essential for achieving a perfect fit.

What you'll need:

A soft measuring tape, an unlined or lightly lined bra and, ideally, a mirror.

STEP 1 | THE UNDERBUST

Your underbust measurement is the circumference of your ribcage measured directly beneath your breasts. It is used to determine your band size.

How to measure your underbust:

Wrap the measuring tape flat under your breasts, parallel to the floor.
Breathe normally. Avoid taking a deep breath or holding your breath.
Take note of the measurement without pulling too tight or leaving too much slack. Between two sizes? Round up to the nearest measurement. Find out your band size.

STEP 2 | THE BUST

Your bust measurement is the circumference of the fullest part of your bust, taken by wrapping a tape measure horizontally around your chest.

How to measure your bust:

Wrap a measuring tape around the fullest part of your bust (at nipple level), keeping it straight and parallel to the floor.
Take note of the measurement without compressing your breasts. The tape should rest lightly against the skin. Between two sizes? Round up the measure.

STEP 3 | THE CUP

The cup indicates breast volume. You determine it by comparing your bust measurement to your underbust measurement.

Step 2
Bust measurement

-

Step 1
Unerbust measurement

=

Difference
Cup letter Find your cup size

INTERPRET YOUR RESULTS

Find Your Band Size

Using your underbust measurement from Step 1, refer to the chart below to find your band size.

STEP 1 MEASUREMENT IN / CM		BAND SIZE CA / US
27 - 28 in	69 - 71 cm	32
29 - 30 in	72 - 76 cm	34
31 - 32 in	77 - 81 cm	36
33 - 35 in	82 - 89 cm	38
36 - 38 in	90 - 96 cm	40
39 - 41 in	97 - 104 cm	42

Find Your Cup Size

Using your result from Step 3, refer to the chart below to find your cup size.

STEP 3 MEASUREMENT IN / CM		CUP SIZE CA / US
1 in	2,5 cm	A
2 in	5 cm	B
3 in	7,5 cm	C
4 in	10 cm	D
5 in	12,5 cm	DD

Concrete example :

You measure 32.5 in under your bust (underbust measurement) → round up to 33 in → band size 38.

You measure 37 in around the fullest part of your bust (bust measurement). 37 – 33 = 4 in → D cup.

Your bra size is 38D.

Is My Bra the Right Fit?

According to Bianca, a few key details can make all the difference. Band fit, strap positioning, and cup comfort are all important factors in finding your perfect bra size.

BAND

UA properly fitting band should feel snug without digging into your sides. It should sit level and not ride up in the back.

STRAPS

Properly adjusted straps should not dig into your shoulders. They should stay in place and lie flat.

CUPS

The right cup size should fully contain and support your breasts.

A properly fitting band should feel snug without digging into your sides. It should sit level and not ride up in the back.

Properly adjusted straps should not dig into your shoulders. They should stay in place and lie flat.

The right cup size should fully contain and support your breasts.

BAND

The band feels too tight, digs into the skin at the sides, and rides up in the back. Your band size may be too small. You should be able to slip two fingers under the band when it is fastened on the middle hooks.

STRAPS

The straps dig into your shoulders. Loosen them so they feel more comfortable. If the problem persists, your band size may be too large.

CUPS

Your breasts spill out of the cups at the front and on the sides. Try a bigger cup size.

The band feels too tight, digs into the skin at the sides, and rides up in the back. Your band size may be too small. You should be able to slip two fingers under the band when it is fastened on the middle hooks.

The straps dig into your shoulders. Loosen them so they feel more comfortable. If the problem persists, your band size may be too large.

Your breasts spill out of the cups at the front and on the sides. Try a bigger cup size.

BAND

It should fit straight across your back, and you should be able to slip maximum two fingers under the band when it is fastened at the middle hooks.

STRAPS

The straps slide off your shoulders. The elastic can stretch over time, so tighten the straps. If they still slip off your shoulders, your bra band size may be too big.

CUPS

The cups crease or are empty at some places. Try a smaller cup size.

It should fit straight across your back, and you should be able to slip maximum two fingers under the band when it is fastened at the middle hooks.

The straps slide off your shoulders. The elastic can stretch over time, so tighten the straps. If they still slip off your shoulders, your bra band size may be too big.

The cups crease or are empty at some places. Try a smaller cup size.

Understanding Bra Sizes

A proper bra fit is about more than just finding the right size. At la Vie en Rose, every bra is designed from the inside out. We get the structure right first—wire shape, cup depth, side support—before adding the details you'll love.

We believe everyone deserves a bra that feels as good as it looks. For us, comfort and style have always gone hand in hand, built together from the very beginning.

What Is the Band?

The band refers to the number in a bra size. It's the horizontal elastic section of the bra that wraps around the ribcage.

The band provides 70 to 80% of a bra’s total support. The straps only stabilize vertically. That’s why a loose band is the leading cause of inadequate support.

Three simple checks to confirm your band size:

The two finger test: you should be able to slide exactly two fingers under the band at your back—no more, no less.
Horizontal fit: the band should sit perfectly straight across your back, without riding up toward your shoulder blades. According to our expert Bianca, it provides most of the support.
The new bra rule: on a brand new bra, always fasten the hooks on the second row from the wing.

What Is a Cup?

The cup is the letter that follows the number in a bra size. It represents breast volume, measured by the difference between your bust measurement at the fullest part of your chest and your band measurement.

What's important to understand: the cup is relative to the band. A 34C cup does not have the same volume as a 38C cup. The larger the band, the greater the volume for the same cup letter.

According to our expert Bianca,
a properly fitting cup should:

Fully support and contain the bust, with no spillage on the sides.
Never gape or pull away from the body. The bra should move with you, not against you.

Sister Sizes

Sister sizes are bra sizes with different numbers and letters that share the same cup volume. They help you adjust the fit to your body while maintaining the same level of coverage and support.

The Sister Size Rule: when you go up one band size (e.g., from 36 to 38), go down one cup letter (e.g., from C to B) to maintain the same volume.

When to use sister sizes? If your usual size is out of stock, if you're between two band sizes, or if you'd like a firmer or more relaxed fit while keeping the same cup volume. We cover this useful tool in full detail in our complete Sister Size Guide.

The Most Common Fitting Mistakes

How to Tell If Your Bra Fits Properly

Straps that slip, a band that rides up, marks on your skin, or cups that gap—these common fit issues are your bra’s way of telling you something. The good news? Once you know what to look for, they’re easy to fix. Fit expert Bianca is here to help you decode the signs and find your perfect fit.

Straps that slide off your shoulders are a sign that your band is too loose. The straps end up overcompensating for the lack of support and eventually slip down.

Bianca's solution:

Go down one band size.
Check that your straps aren't too loose—adjust them until you can slide two fingers underneath, but no more.

A band that rides up toward your shoulder blades is the classic sign that the band is too small. A band that is too tight may not sit properly in place and can be pulled upward.

Bianca's solution:

Go up one band size.
If you've just bought the bra and are already on the loosest hook, something's off—the band is too small for your frame.

Red marks on your back or shoulders can have two very different causes:

Marks on the shoulders: the straps are too tight and/or the band is too loose, which forces the straps to carry all the weight. Loosen the straps and/or go down a band size.
Marks on the back: the band is too small, or the bra is worn out, and the elastic can no longer absorb the pressure. Go up a band size, or replace the bra.

Cups that gape or wrinkle indicate the cup is too large for your breast volume.

Bianca's solutions:

Go down one cup letter (e.g., from C to B).
Try a sister size if the band fits well (e.g., 36C → 34D).
Consider the cup style: moulded (padded) cups tend to gape more easily than lace or soft fabric cups.

EXPERT CHECKLIST

Straps sit comfortably on your shoulders without digging in or slipping off.
You should be able to slide two fingers underneath each strap, snug but never too tight (marks, discomfort) or too wide apart (they slip). The height of the wings (the side panels).
They should provide enough side coverage for comfort and a smoothing effect, especially for everyday wear. The center of the bra.
It should lie flat against your chest. If it lifts, the bra isn’t doing its job properly. The back band is perfectly horizontal.
It shouldn’t ride up toward your shoulder blades. If it does, the band is too small. The cups have no wrinkles and don’t press down.
The cup fabric should be smooth—neither too tight nor too loose. No spillage on the sides or the top. Your breasts are well centered in the cups.
All breast tissue should be contained inside the cup, including the part near the underarm. The elasticity and recovery of the fabric.
A bra should follow the body’s movements while always returning to its shape. You can breathe normally and move your arms without discomfort.
Raise your arms above your head: the bra shouldn’t lift.

These details are invisible when they’re right—but your body feels it immediately when they’re not.

In-store fitting tip: Dans les la Vie en Rose boutiques, our lingerie experts can take your measurements, assess your bust shape, spacing, and projection, and recommend the bra styles, cup types, and sizes that suit you best.

Questions fréquentes sur les tailles de soutiens-gorge

Yes. Sizing is not standardized internationally, and even within the same country, each brand may use its own patterns and construction methods.

What to do:

Always refer to each brand's own size guide.
Try before you buy whenever possible.
For online purchases, check the returns and exchange policy At la Vie en Rose, you have up to 30 days to exchange or return your purchases.

No soft measuring tape on hand? A piece of string, cord, or non-stretch ribbon works just as well. Wrap it around the area you want to measure, keeping it snug but not tight, then mark where it meets. Lay it flat and measure it with a ruler—you’ll get just as accurate a result as with a traditional measuring tape.

Ideally, with an unlined or lightly lined, non padded bra. Padded bras add artificial volume and can throw off your bust measurement, and therefore your cup calculation.

Yes—and that's precisely the principle behind sister sizes. The cup is relative to the band: when you go up one band size, the same breast volume corresponds to one cup letter lower.

The answer varies depending on how often you wear it, how many bras you rotate, how you care for and store it, as well as changes in your body, such as pregnancy, breastfeeding, or weight fluctuations. According to la Vie en Rose experts, the average lifespan of a bra is between 6 and 9 months with regular wear. Not sure if yours has run its course? Our complete guide on bra lifespan has everything you need to know.

Bianca’s advice: If a bra that used to fit you perfectly suddenly doesn’t feel right anymore, trust your body. Refresh your lingerie drawer the same way you update your wardrobe. Your bra should support the woman you are today, not the one you were five years ago.