Bra Size Calculator: Find Your Perfect Fit Online
Enter two simple measurements to estimate your band, cup, and sister sizes. Use the result as a helpful starting point, then check how your bra actually feels.
It estimates a starting bra size from your underbust and full-bust measurements. You will also see nearby sister sizes. The number is a guide—not a rule—because fit can change with the brand, cup shape, fabric, and style.
How to Take Your Measurements
Use a soft measuring tape and keep it level. Measure in a lightly lined or unpadded bra if that feels most comfortable. Accurate placement matters more than pulling the tape tightly.
Enter Your Measurements
Use the same unit for both measurements. Decimals are okay.
Sizing methods vary. Always use comfort and a simple fit check alongside the calculated size.
Estimated Starting Size
Your result will appear here after you enter both measurements.
More Ways to Check Your Fit
Use the calculator you need without repeating the same information.
Sister Size & Band Converter
These two smaller tools help you compare alternatives after you have a starting size.
Sister Size Calculator
Find nearby sizes with similar cup volume and a different band.
Band Size Converter
Compare common US, UK, and EU band labels.
Does Your Bra Feel Right?
Choose the issue you notice most to see a simple next step.
Helpful Fit Resources
Use these pages when you want more detail or personal support.
Bra Size Calculator FAQ
Clear answers about measurement, sizing, and fit.
Start With a Size. Finish With Comfort.
Calculate your starting size, compare sister sizes, and use the fit checker before choosing what feels best.