Professional Bra Size Calculator
Measure Bra Size • Calculate Cup Size • Determine Perfect Fit
Bra Size Calculator & Measurement Tool
🎯 How to Use This Bra Calculator
This professional bra size calculator helps you measure bra size accurately, calculate cup size, and determine your perfect fit. Simply enter your bust measurements, choose your preferred sizing system, and get instant results with detailed sizing charts and fit recommendations.
📏 Measure Your Bra Size
📋 Measurement Guide:
1. Measure under-bust (band size)
2. Measure over-bust (cup calculation)
3. Select measurement system
4. Calculate your perfect bra size!
🎉 Your Calculated Bra Size
Enter your measurements to calculate your perfect bra size
✅ Perfect Fit Checklist:
- Band sits level and snug (80% of support)
- Cups contain all tissue without spillage or gaps
- Center gore lies flat against chest
- Straps stay up without digging in
- You can slide 1-2 fingers under band
How to Measure Bra Size: Complete Guide
Learning how to measure bra size correctly is essential for comfort, health, and confidence. Professional bra fitting involves two key measurements: the band size (under-bust measurement) and the cup size (derived from bust measurement difference). Our comprehensive bra measurement calculator uses proven formulas to determine your perfect fit.
The science of bra cup measurement involves understanding how cup volume changes with band size. Each cup size represents approximately 1 inch of difference between your bust and band measurements, but cup volume scales with band size - this is why sister sizing works and why the same cup letter means different volumes on different bands.
Our bust size calculator incorporates both modern fitting techniques and traditional methods, allowing you to compare different approaches and find the method that works best for your body type and preferences.
Step-by-Step: How to Measure Bra Size
1️⃣ Prepare for Measuring
- Wear proper bra: Well-fitting, non-padded bra or go braless
- Use flexible tape: Soft measuring tape, not rigid ruler
- Get help: Assistant ensures accurate reading
- Stand naturally: Relaxed posture, arms at sides
- Best timing: Mid-cycle, not during hormonal changes
2️⃣ Measure Band Size
- Position: Directly under breast tissue
- Tape tension: Snug but comfortable, no gaps
- Keep level: Parallel to floor all around body
- Breathe normally: Don't hold breath or expand chest
- Record measurement: To nearest quarter inch
3️⃣ Measure Bust Size
- Position: At fullest part of bust
- Tape placement: Over nipples, around back
- No compression: Don't squeeze breast tissue
- Stay level: Tape parallel to ground
- Comfortable fit: Tape should lie flat
4️⃣ Calculate Your Size
- Use calculator: Input measurements above
- Choose method: Modern or traditional approach
- Check sister sizes: Alternative fits available
- Consider fit preference: Snug vs comfortable
- Test the fit: Try on calculated size
Bra Measurement Calculator: The Mathematics
Understanding the mathematics behind bra measurement calculation helps you make informed decisions about fit and sizing methods. Our bra cup size calculator uses proven formulas based on decades of fitting research.
Modern Band Size Formula
Recommended Method:
\[ \text{Band Size} = \text{Round}(\text{Under Bust}) \]
\[ \text{If odd, add 1 for even size} \]
Example: 31" under-bust = 32 band size
Cup Size Calculation
Universal Formula:
\[ \text{Cup} = \text{Bust} - \text{Band Size} \]
0-1": AA/A | 1": A | 2": B | 3": C
4": D | 5": DD/E | 6": DDD/F | 7": G
Traditional +4 Method
Classic Approach:
\[ \text{Band} = \text{Under Bust} + 4 \text{ (if even)} \]
\[ \text{Band} = \text{Under Bust} + 5 \text{ (if odd)} \]
Still used by many retailers
Sister Size Formula
\[ \text{Volume Constant: } Band \downarrow = Cup \uparrow \]
Example: 34C = 32D = 36B
Same cup volume, different band fit
USA Bra Measurement Chart & Size Guide
🇺🇸 USA Band Size Chart (Inches)
| Under-Bust (inches) | Modern Method Band | Traditional +4 Band | Snug Fit Option |
|---|---|---|---|
| 28-29" | 30 | 32-34 | 28 |
| 30-31" | 32 | 34-36 | 30 |
| 32-33" | 34 | 36-38 | 32 |
| 34-35" | 36 | 38-40 | 34 |
| 36-37" | 38 | 40-42 | 36 |
| 38-39" | 40 | 42-44 | 38 |
Note: Green column shows recommended modern method sizing
📏 USA Cup Size Chart
Difference: 0-1"
AA/A Cup
Difference: 1"
A Cup
Difference: 2"
B Cup
Difference: 3"
C Cup
Difference: 4"
D Cup
Difference: 5"
DD/E Cup
Difference: 6"
DDD/F Cup
Difference: 7"
G Cup
Figure Out Bra Size: Common Problems & Solutions
📏 Measurement Problems
- Inconsistent readings: Take multiple measurements
- Tape too loose/tight: Snug but comfortable pressure
- Wrong tape position: Ensure tape stays level
- Measuring over clothing: Wear thin, fitted top only
- Body position changes: Maintain same posture
- Time of month effects: Measure mid-cycle
👙 Common Fit Issues
- Band rides up: Try smaller band size
- Straps fall down: Band likely too big
- Spillage over cups: Try larger cup size
- Gaps in cups: Try smaller cup or different style
- Center doesn't lay flat: Cup too small or wrong shape
- Back bulging: Band too tight or wrong placement
🏷️ Brand & Style Differences
- Size inconsistency: Each brand fits differently
- Different cup shapes: Full cup vs demi vs balconette
- Material stretch: Lace vs cotton vs synthetic
- Country of origin: US vs UK vs EU sizing
- Age of garment: Styles change over time
- Return policies: Always check before purchasing
International Bra Size Conversion Chart
🌍 Band Size Conversion Chart
| USA/UK | European | French | Italian | Australian |
|---|---|---|---|---|
| 30 | 65 | 80 | 1 | 8 |
| 32 | 70 | 85 | 2 | 10 |
| 34 | 75 | 90 | 3 | 12 |
| 36 | 80 | 95 | 4 | 14 |
| 38 | 85 | 100 | 5 | 16 |
| 40 | 90 | 105 | 6 | 18 |
📏 Cup Size Differences by Region
🇺🇸 USA Cups:
A → B → C → D → DD → DDD → G
🇬🇧 UK Cups:
A → B → C → D → DD → E → F → FF
🇪🇺 EU Cups:
A → B → C → D → E → F → G → H
Professional Bra Fitting Tips & Best Practices
🎯 Measurement Excellence
- Measure at same time of day consistently
- Use quality flexible measuring tape
- Take measurements while exhaling naturally
- Record measurements in quarter-inch increments
- Re-measure after weight changes (±5 lbs)
- Compare calculations with actual fit testing
🎪 Smart Size Selection
- Start with calculated size as baseline
- Order sister sizes when shopping online
- Consider your activity level and preferences
- Account for seasonal weight fluctuations
- Factor in bra style and padding differences
- Keep track of what works by brand
✅ Professional Fit Check
- Band provides 80% of support, not straps
- You can slide 1-2 fingers under back band
- Center gore lies flat against breastbone
- No quadruple-boob or spillage over cups
- Underwire sits on ribcage, not breast tissue
- Comfortable for extended wear periods
About the Author
Adam
Co-Founder @ RevisionTown
Math Expert specializing in various curricula including IB, AP, GCSE, IGCSE, and more