Bra Size Converter

A bra size converter is a tool that translates bra measurements between different international sizing systems. Bra sizing varies significantly between countries and regions, which can make shopping for lingerie confusing—especially when purchasing from international brands or shopping online from retailers that use a different sizing standard.

The major sizing systems include US, UK, EU (European), French, Italian, Australian, and Japanese. Each system uses different conventions for both band size and cup size. For example, a US 34C corresponds to a UK 34C, an EU 75C, a French 90C, and an Italian 3C. The cup sizes also vary: a US DD/E is equivalent to a UK DD, but in the EU system it is simply labeled E.

This converter handles both direct size translation between systems and size calculation from actual body measurements. Whether you know your size in one system and need the equivalent in another, or you want to determine your size from fresh measurements, this tool provides accurate results along with sister size recommendations.

Bra size consists of two components: the band size (the number) and the cup size (the letter). The band size corresponds to the measurement around the ribcage directly under the bust, while the cup size represents the difference between the bust measurement at its fullest point and the under-bust measurement.

To calculate band size, measure snugly around the ribcage under the bust. In the US system, if the measurement is an odd number, round up to the next even number. In the UK system, the same rounding applies. EU band sizes use centimeters and are typically 15 larger than the US band size (e.g., US 34 = EU 75, where 34 × 2.54 ≈ 86, but EU uses 75 as a standard band).

Cup size is determined by the difference between the bust measurement (at the fullest point) and the under-bust measurement. A 1-inch difference corresponds to an A cup, 2 inches to B, 3 inches to C, 4 inches to D, and so on. The cup letter system varies by region, which is why conversion tables are necessary.

This calculator offers two modes of operation:

1. Size Conversion Mode: Select your known US band size and cup size from the dropdown menus. The calculator instantly displays your equivalent size in US, UK, EU, French, Italian, Australian, and Japanese systems. It also shows your sister sizes—alternative sizes with the same cup volume but different band lengths.
2. Measurement Mode: Enter your under-bust and bust measurements in either inches or centimeters. The calculator determines your band size and cup size based on the difference between these two measurements, then displays the result in US sizing.
3. Review Sister Sizes: If your calculated or selected size does not feel quite right, try the sister sizes shown. Sister sizes maintain the same cup volume with a different band, which can help when a specific size feels tight or loose.

Remember that sizing varies between brands and manufacturers. This converter provides a reliable starting point, but trying on bras remains the best way to confirm fit.

The conversion results show your bra size across seven international sizing systems. The US and UK systems are identical for most sizes, diverging only at larger cup sizes where the UK uses double letters (DD, EE, FF) while the US combines them (DD/E, DDD/F).

EU sizing uses centimeter-based band numbers (60, 65, 70, 75, 80, etc.) and a simpler letter-based cup system. French sizing adds approximately 15 to the EU band number. Italian sizing uses a different numbering system entirely, starting from 0 for the smallest band.

Sister sizes are particularly useful because they share the same cup volume. If you go down one band size, you go up one cup size to maintain the same volume, and vice versa. For example, 34C has sister sizes 32D (smaller band, larger cup letter) and 36B (larger band, smaller cup letter).

International shopping is the primary use case for bra size conversion. When purchasing lingerie from European, Japanese, or UK brands, knowing your equivalent size in that system ensures a proper fit. Many online retailers list sizes in multiple systems, but a converter gives you confidence in your selection.

Online purchases from international retailers require size knowledge in the seller's system. A UK brand may list sizes in UK measurements, while a Japanese brand uses JP sizing. Without conversion, you risk ordering the wrong size and dealing with costly returns.

Post-surgery and body changes can shift your bra size. After weight loss, pregnancy, or breast surgery, remeasuring and using the measurement calculator helps you find your new correct size. The measurement mode of this tool makes it easy to recalculate from scratch.

Fitness and comfort depend on wearing the right size. Studies suggest that a large percentage of women wear the wrong bra size, which can cause discomfort, poor posture, and inadequate support. Regular measurement and conversion checking helps ensure ongoing comfort and proper fit.