Find Out My Bra Size Calculator
Bra Size Calculator
Enter your measurements below to estimate your bra size. For best results, measure without a bra or with a non-padded, non-minimizer bra.
Measurement Comparison
What is a Find Out My Bra Size Calculator?
A find out my bra size calculator is an online tool designed to estimate your bra size based on body measurements you provide. Typically, you need to measure your under bust (rib cage just below your breasts) and the fullest part of your bust. The calculator then uses a formula to suggest a band size and cup size.
Anyone who wears a bra and is unsure of their current size or wants to check their fit can use a find out my bra size calculator. It's particularly useful if you've experienced changes in body weight, after pregnancy, or if you feel your current bra isn't providing the right support or comfort.
Common misconceptions include thinking that bra sizes are universal across all brands (they vary significantly), or that cup size is the only important factor (band size is crucial for support). Another is that if you go up a cup size, you just change the letter – but cup volume is relative to the band size.
Find Out My Bra Size Calculator Formula and Mathematical Explanation
The most common methods for a find out my bra size calculator involve two key measurements and calculations:
- Band Size Calculation:
- Measure snugly around your rib cage, just under your bust, keeping the tape level.
- Modern Method (Used in our calculator): If using inches, round the under bust measurement up to the nearest even number. For example, 29.5 inches rounds up to 30, 30 stays 30, and 31 rounds up to 32. This is your band size.
- Older Method (+4/+5): Some older methods add 4 inches to an even under bust measurement or 5 inches to an odd one to get the band size. This method is less common now, especially for band sizes 36 and above, as it can lead to a band that is too loose.
- Cup Size Calculation:
- Measure loosely around the fullest part of your bust, keeping the tape level and not too tight.
- Subtract your calculated band size from your bust measurement (both in inches).
- The difference in inches determines the cup size:
- 0″ = AA
- 1″ = A
- 2″ = B
- 3″ = C
- 4″ = D
- 5″ = DD or E
- 6″ = DDD or F
- 7″ = G
- And so on…
For example, if your under bust is 31 inches and your bust is 36 inches:
- Band Size: 31 rounded up to the nearest even number is 32.
- Difference: 36 (bust) – 32 (band) = 4 inches.
- Cup Size: A 4-inch difference usually corresponds to a D cup.
- Estimated Size: 32D
Here's a table of variables used:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Under Bust Measurement | Circumference of the rib cage just below the breasts | Inches or cm | 24-50 inches (60-127 cm) |
| Bust Measurement | Circumference around the fullest part of the bust | Inches or cm | 26-60 inches (66-152 cm) |
| Band Size | The number part of the bra size, based on the under bust | Inches (even numbers) | 28-56 |
| Cup Difference | Bust Measurement – Band Size | Inches | 0-15+ |
| Cup Size | The letter part of the bra size, based on the difference | Letter (AA, A, B, C…) | AA-M+ |
Our find out my bra size calculator uses the "round up to nearest even" method for the band size, as it generally provides a more supportive fit than the older "+4/+5" method.
Practical Examples (Real-World Use Cases)
Example 1:
- Under Bust Measurement: 29 inches
- Bust Measurement: 33 inches
- Unit: Inches
- Band Size: 29 rounded up to nearest even = 30
- Difference: 33 – 30 = 3 inches
- Estimated Bra Size: 30C
Example 2:
- Under Bust Measurement: 90 cm (approx 35.4 inches)
- Bust Measurement: 105 cm (approx 41.3 inches)
- Unit: cm converted to inches for calculation
- Under Bust (inches): ~35.4 inches -> Band Size: 36
- Bust (inches): ~41.3 inches
- Difference: 41.3 – 36 = 5.3 inches (closer to 5)
- Estimated Bra Size: 36DD (or 36E depending on brand)
These examples illustrate how the find out my bra size calculator works with different measurements.
How to Use This Find Out My Bra Size Calculator
- Select Unit: Choose whether you are entering measurements in inches or centimeters.
- Enter Under Bust Measurement: Measure around your rib cage just under your bust. Enter the value. Ensure the tape is snug but not digging in.
- Enter Bust Measurement: Measure around the fullest part of your bust. The tape should be level and not too tight, just skimming the body. Enter the value.
- Calculate: The calculator will automatically update the results as you type, or you can click "Calculate Size".
- Read Results: The primary result is your estimated bra size (e.g., 34C). You'll also see the calculated band size, cup letter, and the difference used.
- Check Sister Sizes: The table will show sister sizes – sizes with the same cup volume but different band lengths. This is useful if the calculated band feels too tight or loose.
- Consider the Fit: The result is a starting point. Always try bras on, as different bra types and brands fit differently. Check for a snug band, cups that don't gap or overflow, and comfortable straps.
Key Factors That Affect Find Out My Bra Size Calculator Results
- Accuracy of Measurement: How snugly or loosely you hold the tape measure can significantly alter the readings and the resulting size from the find out my bra size calculator.
- Bra Brand Variations: Different manufacturers use different sizing standards. A 34C in one brand might fit differently than a 34C in another. See our bra fitting tips for brand advice.
- Bra Style and Type: Plunge bras, full-cup bras, balconettes, and sports bras are constructed differently and may fit differently even in the same size.
- Body Changes: Weight fluctuations, hormonal changes (like during your menstrual cycle or pregnancy), and age can affect breast size and shape, requiring a size re-evaluation.
- Time of the Month: Breasts can swell before or during menstruation, so measuring at different times might give slightly different results.
- Posture: Slouching versus standing straight can affect measurements. Stand tall with your shoulders back when measuring.
- The "Vanity Sizing" Myth: While less common in bras than clothes, some brands might alter sizing slightly for marketing. Always trust the fit over the label.
Frequently Asked Questions (FAQ)
1. How accurate is a find out my bra size calculator?
A find out my bra size calculator provides a good starting point, but it's an estimate. The best way to find your perfect size is to try on bras after using the calculator, paying attention to fit guides and how the bra feels. Many people get a more accurate result than they expect.
2. Should I measure with or without a bra on?
It's best to measure without a bra or while wearing a thin, non-padded, non-molded bra to get the most accurate measurements of your natural shape.
3. What if my measurements put me between band or cup sizes?
If you're between band sizes, consider the smaller band with a larger cup (sister size) for more support, or the larger band with a smaller cup if the smaller band feels too tight. For cup sizes, try both the smaller and larger cup to see which fits best without gapping or spillage.
4. What are sister sizes?
Sister sizes are bra sizes that have the same cup volume but different band sizes. For example, 34B, 32C, and 36A are sister sizes. If your band is too loose in a 34B, you might try a 32C. Our understanding sister sizes guide explains more.
5. How often should I use a find out my bra size calculator?
It's a good idea to remeasure and use a find out my bra size calculator every 6-12 months, or after significant weight changes, pregnancy, or if your bras start to feel uncomfortable.
6. Why does the band size calculation add inches or round up?
The band size needs to be snug to provide support. Historically, +4/+5 was used because bra materials had less stretch. Modern methods like rounding up to the nearest even number often reflect the stretch in current materials better and give a firmer, more supportive band.
7. What are common signs of a poor bra fit?
Bands riding up your back, straps digging in or falling off, cups gapping, breast tissue spilling out of the cups or under the band, or any discomfort are signs of a poor fit. Check our guide on common bra fit problems.
8. Does cup size increase with band size (e.g., is a 38B the same cup volume as a 34B)?
No, cup size is relative to the band size. A 38B has a larger cup volume than a 34B. The letter (B) represents a 2-inch difference between bust and band, but the overall volume is larger on a 38 band.