Find Your Perfect Fit with the Bra Size Calculator
Wearing the right bra size is more than a matter of comfort — it directly affects your posture, physical health, and self-confidence. Our Bra Size Calculator at BestCalculator.io is designed to help you find your accurate bra size using just two simple measurements: your band (underbust) and bust (overbust). With a fast, accurate result based on standard fitting principles and international size charts, this tool eliminates the guesswork and helps you feel supported every day.
Bra Size Calculator
| Location | Size | Cup |
|---|---|---|
| US/CA | -- | -- |
| UK | -- | -- |
| EU | -- | -- |
| FR/BE/ES | -- | -- |
| Australia/NZ | -- | -- |
| Location | Size | Cup |
|---|---|---|
| US/CA | -- | -- |
| UK | -- | -- |
| EU | -- | -- |
| FR/BE/ES | -- | -- |
| Australia/NZ | -- | -- |
1. Band Size: Round your underbust measurement
2. Cup Size: Subtract band size from bust measurement
Example:
Underbust 80cm, Bust 93cm → Band 80, Difference 13cm → EU 80C
Wearing the Wrong Bra Size? You’re Not Alone
It’s estimated that 70% to 85% of women wear bras that don’t fit properly. Many unknowingly choose a band that’s too loose and a cup that’s too small, which leads to discomfort, poor support, and even back pain. A major reason for this widespread problem is the lack of standardized sizing. Bra sizes can vary across countries, brands, and even styles — meaning a 34B in one brand might not fit the same as a 34B in another.
That’s why we created this calculator: to bring clarity and consistency to something as essential as everyday comfort.
How to Know If Your Bra Doesn’t Fit Right
Here are some common signs your current bra size might be off:
The band rides up your back or digs into your skin
Straps leave red marks or fall off your shoulders
Breasts spill out of the cups or there’s gaping
The center panel doesn’t sit flat against your chest
If you’re experiencing any of these issues, it’s a good time to recheck your measurements and let our calculator recommend your true size.
How the Bra Size Calculator Works
Our tool uses a proven formula:
Band Size (Underbust Measurement) – This is taken directly under the bust.
Bust Size (Overbust Measurement) – This is the fullest part of your chest.
The difference between these two measurements determines your cup size, while the band size corresponds to the width of your torso. Our calculator quickly computes your correct bra size based on standardized sizing systems used in the U.S., U.K., Australia, and Europe.
Understanding Bra Sizes: Band & Cup
Band Size (Underbust)
Your band size is based on the circumference around your rib cage. Because regional sizing differs, here’s a quick comparison chart:
| Size | FR/BE/ES | EU | US/UK | AU/NZ |
|---|---|---|---|---|
| XXS | 75 | 60 | 28 | 6 |
| XS | 80 | 65 | 30 | 8 |
| S | 85 | 70 | 32 | 10 |
| M | 90 | 75 | 34 | 12 |
| L | 95 | 80 | 36 | 14 |
| XL | 100 | 85 | 38 | 16 |
| XXL | 105 | 90 | 40 | 18 |
| 3XL | 110 | 95 | 42 | 20 |
| 4XL | 115 | 100 | 44 | 22 |
Cup Size (Bust Difference)
Cup size is calculated by subtracting the band size from the bust size. Here’s how that difference translates into common cup sizes:
US/UK/AU Cup Sizes (in Inches)
| Bust – Band (inches) | Cup Size |
|---|---|
| <1 | AA |
| 1 | A |
| 2 | B |
| 3 | C |
| 4 | D |
| 5 | DD or E |
| 6 | DDD or F |
| 7 | G |
| 8 | H |
| 9 | I |
| 10 | J |
| 11 | K |
| 12 | L |
European Cup Sizes (in CM)
| Bust – Band (cm) | EU Cup |
|---|---|
| 10–11 | AA |
| 12–13 | A |
| 14–15 | B |
| 16–17 | C |
| 18–19 | D |
| 20–21 | E |
| 22–23 | F |
| 24–25 | G |
| 26–27 | H |
| 28–29 | I |
| 30–31 | J |
| 32–33 | K |
Real-World Examples
Example 1: The Professional on the Go
Monica, a business consultant, was tired of feeling uncomfortable in her bras during long client meetings. She used our Bra Size Calculator and discovered she was wearing a 36B, but her true size was a 34D. The switch made her feel more secure and significantly improved her posture and energy during the day.
Example 2: The Fitness Enthusiast
Lena, a college athlete, struggled with sports bras that didn’t stay in place. Using the calculator, she found her actual size was 32C. With the correct size, her new sports bra offered the stability she needed for high-impact workouts.
Who Benefits from the Bra Size Calculator?
This tool is made for everyone — whether you’re a student, working professional, new mom, or someone undergoing body changes due to weight fluctuation or pregnancy. It’s especially useful for:
First-time bra buyers needing accurate guidance
Online shoppers trying to avoid size guesswork
Anyone feeling discomfort with current bras
Health-conscious users seeking better posture and support
Final Thoughts: Support You Can Feel
Getting the right bra size is more than a convenience — it’s a self-care decision. With the Bra Size Calculator from BestCalculator.io, you can eliminate the guesswork, reduce discomfort, and feel supported throughout your day. Start with your measurements and let us do the rest.
Because your best fit should feel like you’re wearing nothing at all — but better.