Bra Size Calculator

How Bra Sizing Works

A bra size consists of two components: a band size (the number) and a cup size (the letter). The band size represents the measurement around your ribcage, directly under your bust. The cup size represents the difference between your bust measurement and your band measurement.

This calculator uses the standard method where each inch of difference between your bust and band measurements corresponds to one cup size. A 1-inch difference is an A cup, 2 inches is a B cup, and so on. The band size is calculated by rounding your underbust measurement to the nearest even number.

How to Take Your Measurements

Accurate measurements are essential for a reliable result. Use a soft measuring tape and follow these steps:

• Band measurement (underbust): Measure directly under your bust, keeping the tape snug and level around your ribcage. The tape should be tight enough to stay in place but not dig into your skin. Exhale normally while measuring.
• Bust measurement: Measure around the fullest part of your bust, keeping the tape parallel to the floor. Do not pull the tape tight — it should sit comfortably against your skin without compressing breast tissue.

Take both measurements in inches. If you measure in centimeters, convert to inches first (1 inch = 2.54 cm) for the most accurate result with this calculator.

Understanding Your Results

The calculator provides a standard bra size based on your inputs. This is a starting point, not a definitive fit guarantee. Bra fit varies between brands, styles, and individual body shapes.

Your result includes a band size (e.g., 34, 36, 38) and a cup size (e.g., B, C, D). For example, a result of "34C" means a band size of 34 inches and a cup size that corresponds to a 3-inch difference between bust and band measurements.

If your measurements fall between standard sizes, the calculator rounds to the nearest standard size. This is normal and expected.

Common Fit Issues

Even with a correctly calculated size, fit problems can occur. Here are the most common issues and what they typically indicate:

• Band rides up in the back: The band may be too large. Try a smaller band size.
• Straps dig into shoulders: The band may be too large and carrying too much weight. Try a smaller band size.
• Cups gap or wrinkle: The cup may be too large. Try a smaller cup size.
• Breasts spill over the top or sides: The cup may be too small. Try a larger cup size.
• Band feels too tight: Try a larger band size and adjust the cup size accordingly (sister sizing).

Sister Sizing

Sister sizing is a concept where you can adjust your band and cup sizes together while maintaining the same cup volume. For example, a 34C has the same cup volume as a 32D (smaller band, larger cup) and a 36B (larger band, smaller cup).

If your calculated size doesn't feel right, try sister sizes. This is especially useful if you are between band sizes or if a particular brand runs large or small in the band.

Limitations of This Calculator

This calculator provides an estimate based on standard sizing conventions. It does not account for:

• Variations in sizing between different brands or countries
• Differences in breast shape, density, or asymmetry
• Specific style requirements (e.g., sports bras, plunge bras, full-coverage bras)
• Posture or body composition factors that affect measurement accuracy

Always try on bras before purchasing when possible, and use this result as a guide rather than an absolute size.