Our calculator uses industry-standard algorithms and provides accurate results when measurements are taken correctly. However, fit can vary between brands, so we recommend using the calculated size as a starting point and trying on different sizes.

You need two measurements: band size (around your ribcage, just below your bust) and bust size (around the fullest part of your bust). Both measurements should be taken with a soft, flexible tape measure.

Wrap a tape measure around your ribcage, just below your bust. The tape should be snug but not tight, and you should be able to breathe comfortably. Make sure the tape is level all around.

Wrap the tape measure around the fullest part of your bust, typically at nipple level. The tape should be level and not too tight. Breathe normally while taking this measurement.

A properly fitting bra should have a band that sits level around your ribcage without riding up, straps that don't dig into your shoulders, and cups that fully contain your breasts without spillage or gaps. The center gore should lie flat against your chest, and you should be able to fit two fingers under the band comfortably.

US and UK bra sizes share the same band size system (measured in inches), but differ in cup size notation. UK sizes use double letters for larger cup sizes (DD, FF, GG, HH, etc.) while US sizes typically use single letters (D, F, G, H, etc.). Our calculator automatically converts between these systems.

Experts recommend measuring your bra size every 6-12 months, or whenever you experience significant body changes such as weight fluctuations, pregnancy, breastfeeding, menopause, or fitness transformations. Regular measurements ensure you're always wearing the correct size.

Bra size variations between brands occur due to different sizing standards, fit models, and manufacturing processes. Some brands run small (like many European brands), while others run large (common with some US brands). Always try on bras when possible.

If you're between sizes, start with the larger size as it's easier to adjust a slightly large bra than one that's too small. Consider trying different styles - balconette, full-cup, plunge, and demi-cup bras all fit differently even in the same size.

Cup sizes represent the difference between your band size and bust size. Each cup size represents approximately a 1-inch difference: A = 1 inch, B = 2 inches, C = 3 inches, D = 4 inches, DD = 5 inches, and so on. However, the actual volume varies by band size.

Bra size conversion varies by country and region. US/UK use inches for band sizes, while EU countries use centimeters. Cup size progressions also differ. Our comprehensive size charts show exact conversions for US, UK, EU, French, Japanese, Korean, German, Italian, and many other international sizing systems.

Falling straps usually indicate a band that's too loose or cups that are too small. The band should provide 80% of the support, with straps only providing 20%. If straps are falling, first check if your band size is correct using our calculator.

While a tape measure is most accurate, you can use a piece of string or ribbon to measure, then measure the string against a ruler. For band size, wrap the string around your ribcage below your breasts. For bust size, wrap it around the fullest part of your breasts.

Padded bras have additional lining or foam to enhance shape and provide more coverage, while unpadded bras are made of fabric only. When measuring for bra size, wear an unpadded bra or no bra at all for the most accurate measurements.

Significant weight changes (typically 10-15 pounds or more) usually require a new bra size. Weight loss often means going down in band size, while weight gain may require going up. Use our calculator to get your new measurements and compare with your current size.

Sister sizes are bras with the same cup volume but different band sizes. For example, 32D, 34C, and 36B all have the same cup volume. If your band size changes, you can go up or down in band size and adjust the cup size accordingly.

Sports bra sizing uses the same measurements as regular bras - band size and bust size. However, sports bras often run smaller and provide more compression. For high-impact activities, you might want to go down a cup size for more support.

European bra sizes use centimeters for band measurements (60, 65, 70, 75, etc.) while American sizes use inches (28, 30, 32, 34, etc.). European cup sizes also follow a different progression. Our calculator automatically converts between these systems.

A bra that's too tight will cause red marks, discomfort, and difficulty breathing. A bra that's too loose will ride up in the back, provide insufficient support, and cause straps to fall. The band should be snug but comfortable, allowing you to fit two fingers underneath.

Measure in the morning when your body is at its most natural state, before any swelling from daily activities. Avoid measuring right after exercise or when you're bloated. For the most accurate results, measure without a bra or in an unpadded bra.

Hand wash bras in cold water with mild detergent, or use a gentle cycle in a mesh bag. Avoid fabric softeners and bleach. Air dry bras instead of using a dryer, as heat can damage elastic. Replace bras every 6-12 months or when they lose their shape.

If your measurements fall between sizes, try both sizes. Different brands may fit differently, and personal preference also plays a role. Start with the calculated size and adjust based on how the bra feels.

It's recommended to measure yourself every 6-12 months, or whenever you notice changes in your body due to weight fluctuations, pregnancy, or other factors that might affect your size.

US and UK sizing use the same band size system but may differ in cup size progression. Our calculator provides results in both systems, and you can use our size charts to compare international sizes.

Each brand has its own sizing standards and fit preferences. Some brands run small, others run large. It's always best to try on bras before purchasing, especially when trying a new brand.

Sister sizes have the same cup volume but different band sizes. For example, 34C and 32D have the same cup volume. If your calculated size doesn't fit well, try the sister size.

A well-fitting bra should have a band that stays in place, cups that fully contain your bust without spillage, straps that don't dig in, and a center gore that lies flat against your chest.