en (INR)
Bra Size Guide: How to Find Your Perfect Fit?
What you'll need:
A soft measuring tape, an unlined or lightly lined bra and, ideally, a mirror.
Step 2
Bust measurement
Step 1
Underbust measurement
Difference
Cup letter
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.
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
Why Do My Bra Straps Keep Falling Off?
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.
Why Does My Bra Ride Up at the Back?
A band that rides up toward your shoulder blades is the classic sign that the band is too big. A band that is too loose may not sit properly in place and can be pulled upward.
Bianca's solution:
- Go down one band size.
- If you've just bought the bra and are already on the tightest hook, something's off—the band is too big for your frame.
Why Does My Bra Leave Marks?
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.
Why Are My Cups Wrinkled or Gaping?
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.
These details are invisible when they’re right—but your body feels it immediately when they’re not.
In-store fitting tip: In 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.
Frequently Asked Questions About Bra Sizes
Do Bra Sizes Vary Between Brands?
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.
How Can I Measure Without a Measuring Tape?
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.
Should I Measure With or Without a Bra On?
Ideally, with anunlinedorlightly lined, non padded bra. Padded bras add artificial volume and can throw off your bust measurement, and therefore your cup calculation.
Does the Cup Change When I Change Band Size?
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.
How Often Should I Replace My Bra?
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.