Bra Size Calculator

An ill-fitting bra is one of the most common wardrobe problems — and most women are wearing the wrong size without knowing it. This bra size calculator helps you find your correct size in US, UK, and EU sizing using just two measurements.

What Does This Calculator Do?

Enter your band measurement (underbust) and bust measurement (fullest part), and the calculator returns your bra size in multiple international sizing systems.

How to Measure

1. Band size: Measure around your ribcage directly under your bust (underbust), snug but not tight. Record in inches.
2. Bust size: Measure around the fullest part of your bust, keeping the tape parallel to the ground. Record in inches.
3. Enter both measurements and click Calculate.

Bra Size Formula

Band size: Round underbust to nearest even number (add 1 if underbust is odd).

Cup size: Bust measurement minus band size = difference in inches → determines cup letter.

• 0 inches = AA, 1 inch = A, 2 inches = B, 3 inches = C, 4 inches = D, 5 inches = DD/E, 6 inches = DDD/F

Example Calculation

Underbust = 31 inches, Bust = 36 inches.

• Band size: 31 → round up to 32
• Cup difference: 36 − 32 = 4 inches → D cup
• Result: 32D

International Size Conversion

• US 32D = UK 32D = EU 70D = FR/ES 85D = IT 2D
• US 34B = UK 34B = EU 75B = FR/ES 90B
• US 36C = UK 36C = EU 80C = FR/ES 95C

Common Mistakes to Avoid

• Measuring with a padded bra on — always measure without a bra or in a non-padded, unlined bra for accuracy.
• Pulling the tape too tight — the tape should be snug but you should be able to fit one finger beneath it.
• Using the same size across all brands — bra sizing varies significantly between brands. Always try before you buy, or check brand-specific size charts.

Frequently Asked Questions

How do I know if my bra fits correctly?

The band should be level and firm (not riding up). The center gore should lie flat against your sternum. Cups should fully contain the breast without spillage or gaps. Straps should not dig in or fall off.

What does sister sizing mean?

Sister sizes have the same cup volume but different band sizes. If 34C doesn't fit, try 36B (larger band, smaller cup) or 32D (smaller band, larger cup).

Should I measure my bra size at home or in a store?

Home measuring is a good starting point. However, a professional fitting at a lingerie store can fine-tune the result — it's usually free.

Why do US and UK sizes look the same but fit differently?

Band sizes are equivalent, but cup sizing diverges at larger sizes. A US DDD = UK F. For larger cup sizes always verify on brand-specific charts.

How often should I remeasure my bra size?

After significant weight change, pregnancy, or nursing — and generally every year or two, as body composition naturally changes over time.

Conclusion

A well-fitting bra improves comfort, posture, and the look of clothing. Take two minutes to measure and use this calculator — it could change how comfortable you feel every single day.

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