What is the Bra Size Calculator?
The bra size calculator is a free online tool that helps you work out bra size quickly and accurately. It uses the standard formula Band from underbust; cup from the bust-minus-underbust difference and shows the result instantly as you type, along with a full breakdown so you can see exactly how the answer was reached.
How to use this calculator
- Measure snugly under the bust.
- Measure around the fullest part.
- See an estimated size.
Formula used
Band from underbust; cup from the bust-minus-underbust differenceExplanation of each input
- Underbust measurement (cm) โ the underbust measurement used in the calculation.
- Bust measurement (cm) โ the bust measurement used in the calculation.
Understanding your result
- Band size โ the calculated band size.
- Cup difference โ the calculated cup difference in cm.
Step-by-step calculation
For the example values underbust 75, bust 90:
- Apply the formula:
Band from underbust; cup from the bust-minus-underbust difference - Substitute the values: difference 15 cm
- Result: estimated band and cup
Worked example
| Inputs | underbust 75, bust 90 |
|---|---|
| Working | difference 15 cm |
| Result | estimated band and cup |
Benefits and practical uses
This calculator saves you time and reduces errors when you need bra size. It is useful for students, professionals and anyone who wants a fast, reliable answer without manual calculation. Results update instantly, work in your browser and can be copied or shared in one click.
Assumptions and limitations
- Measurements in centimetres; estimate only.
Frequently asked questions
Why do sizes vary by brand?
Sizing standards differ between brands and countries, so always try before buying.
Disclaimer: This calculator provides general estimates for educational purposes only and is not medical advice. Consult a qualified healthcare professional for personal guidance.