Boob & Bust Calculator
Accurately measure your bust size, calculate cup volume, and get personalized bra size recommendations with our professional measurement tool.
Enter Your Measurements
Measure snugly around your ribcage, directly under your breasts
Measure around the fullest part of your bust
Measure across the top of your bust, above breast tissue
Your Results
Band Size Formula:
Cup Size Formula:
Cup Volume (Hemisphere Approximation):
Where r = radius of breast base, h = projection height
Practical Volume Estimate:
A cup ≈ 175ml, B cup ≈ 350ml, C cup ≈ 525ml, D cup ≈ 700ml
How to Measure Your Bust Size
Wear an Unpadded Bra
For accuracy, wear a well-fitting unpadded bra or measure without a bra while standing upright.
Measure Your Underbust
Wrap a soft tape snugly around your ribcage, directly under your breasts. Keep tape level and parallel to the floor. This is your band measurement.
Measure Your Full Bust
Measure around the fullest part of your bust (usually at nipple level). Keep tape level without compressing breast tissue.
Optional: Measure Overbust
For fuller analysis, measure across your chest above the breast tissue. This helps determine breast projection.
Calculate Your Size
Enter all measurements into the calculator above to get your bust size, bra recommendations, and cup volume estimate.
Bust & Cup Size Reference Chart
| Difference (in) | US Cup | UK Cup | EU Cup | Volume (ml) |
|---|---|---|---|---|
| 0-1" | AA | AA | AA | ~100 |
| 1" | A | A | A | ~175 |
| 2" | B | B | B | ~350 |
| 3" | C | C | C | ~525 |
| 4" | D | D | D | ~700 |
| 5" | DD/E | DD | E | ~875 |
| 6" | DDD/F | E | F | ~1050 |
| 7" | G | F | G | ~1225 |
| 8" | H | FF | H | ~1400 |
| 9" | I | G | I | ~1575 |
| 10" | J | GG | J | ~1750 |
Understanding Bust Measurements
📏 Bust Circumference
The measurement around the fullest part of your bust. This determines your overall bra size when combined with band measurement.
🎯 Band Size
Based on your underbust measurement, rounded to the nearest even number. The band provides 80% of bra support.
☕ Cup Size
Determined by the difference between bust and band measurements. Each inch represents one cup size increase.
📊 Cup Volume
The actual volume of breast tissue, typically measured in ml or cc. Useful for understanding breast asymmetry and surgical planning.
Pro Measurement Tips
- Measure at the same time of day for consistency (breasts can change size throughout the day)
- Stand in front of a mirror to ensure the tape is level all around
- Take 2-3 measurements and use the average for best accuracy
- The tape should be snug but not tight enough to indent the skin
- Consider measuring during different times of your menstrual cycle as size can fluctuate
Frequently Asked Questions
Wear an unpadded bra or no bra. First, measure around your ribcage directly under your bust for the band size. Then measure around the fullest part of your bust, keeping the tape parallel to the floor. The difference between these measurements determines your cup size.
Bust size refers to your actual body measurement in inches or centimeters. Bra size is a combination of your band size (underbust measurement) and cup size (the difference between bust and band), expressed as numbers and letters like 36C or 38DD.
Cup volume can be calculated using the hemisphere formula: V = (π/3) × h² × (3r - h), where r is the breast base radius and h is the projection. For practical purposes, each cup size represents approximately 175ml increase in volume.
Brands use different sizing standards, manufacturing methods, and fit models. Additionally, US, UK, and EU sizing systems differ significantly. Always check each brand's specific size chart and try on bras when possible.
Measure every 6-12 months, or after weight changes of 10+ pounds, pregnancy, breastfeeding, hormonal changes, or if your current bras feel uncomfortable. About 80% of women wear incorrect bra sizes.
Related Calculators
Official Resources & References
Created by OmniCalculator.space | Last Updated: January 2026