You can accurately measure your bra size at home with just a soft fabric measuring tape and a mirror. First, measure your underbust by wrapping the tape around your ribcage directly under your breasts, keeping it snug but comfortable and parallel to the floor. Record this number. Next, measure around the fullest part of your bust, leaning forward slightly to capture all breast tissue. Keep the tape level and not too tight. Record this second number. Subtract your underbust from your bust measurement - each inch of difference equals one cup size (1"=A, 2"=B, 3"=C, etc.). Your underbust measurement rounded to the nearest even number is your band size. If you need help, ask a family member or friend to hold the tape while you check positioning in the mirror for the most accurate results.

The most accurate method is the UK sizing technique using a professional fitting or careful self-measurement without a bra. Use a soft fabric measuring tape (not a rigid ruler), measure your underbust snugly where the band sits, then measure your bust at the fullest point while leaning forward slightly. Use the UK method which doesn't add inches to your underbust - simply round to the nearest even number for your band size. Take each measurement twice to verify accuracy. The best time to measure is mid-cycle (not during your period when breasts may be swollen) and in the morning before eating or drinking when there's less bloating. Having a professional bra fitter verify your measurements at a specialty lingerie store provides the gold standard for accuracy, especially if you've never been professionally fitted before.

For large breasts, accurate measurement requires special attention to ensure the tape stays in position. When measuring your underbust, make sure the tape sits firmly without rolling or riding up - you may need to hold it in place. For the bust measurement, lean forward at a 90-degree angle so your breasts hang naturally away from your chest wall, ensuring you capture their full volume. Have someone help you hold the tape level across your back while you check the front in a mirror. Many people with large breasts discover they need much larger cup sizes than expected - DD, E, F, FF, G, or beyond are common and normal. Don't be discouraged by letter sizes; they simply indicate volume. Look for brands that specialize in full-bust sizing like Panache, Freya, or Elomi, which offer better support structures for larger breasts. Professional fitting at a specialty boutique is highly recommended for large busts to find styles that provide proper support, lift, and comfort.

Cup size is determined by the difference between your bust measurement (fullest part) and your band size (underbust). Subtract your band size from your bust measurement and the result tells you your cup size. Here's the complete progression: less than 1 inch = AA cup, 1 inch = A cup, 2 inches = B cup, 3 inches = C cup, 4 inches = D cup, 5 inches = DD/E cup, 6 inches = DDD/F cup, 7 inches = G cup, 8 inches = H cup, 9 inches = HH cup, 10 inches = J cup, and so on. Cup sizes are relative to band size - a 34D has the same cup volume as a 32DD or 36C (these are called sister sizes). When trying on bras, your breasts should fill the entire cup without gaps or spillage. The cup should contain all your breast tissue, the underwire should sit on your ribcage (not on breast tissue), and the center gore should touch your sternum. If you're experiencing quad-boob effect (tissue spilling over the top), go up a cup size. If there are gaps or wrinkles in the cups, go down a cup size.

Measuring for your first bra uses the same techniques as adult bra sizing but often results in smaller band and cup sizes. Measure your underbust where a bra band would sit, typically 28-34 inches for most teens. Then measure around the fullest part of your developing breast tissue. Training bras and first bras often come in size ranges rather than specific band/cup combinations - XS, S, M, L or numbered sizes 1-4. To convert measurements to these simplified sizes: XS/1 typically fits 28-30 inch chest, S/2 fits 30-32 inches, M/3 fits 32-34 inches, L/4 fits 34-36 inches. If you're buying a bra with traditional sizing, start with the smallest cup size (AA or A) in your band size and adjust from there. Sports bras or soft-cup bralettes make excellent first bras because they're more forgiving in fit. Don't feel embarrassed about your size - everyone develops at different rates and times, and all breast sizes are completely normal. Consider shopping with a trusted adult or asking a store employee for help if you're unsure.

Yes, measuring without a bra is actually the preferred and most accurate method because padded bras, molded cups, and push-up bras add bulk that throws off your true measurements. Professional fitters recommend measuring either completely bare-chested or wearing only a very thin, unpadded bra. When measuring without a bra, your breast tissue hangs naturally in its true shape and position, giving you authentic measurements. For the bust measurement, lean forward at a 90-degree angle so your breasts hang away from your body - this ensures you capture all breast tissue, including what normally rests against your chest wall. The underbust measurement can be taken standing upright. Some people feel more comfortable measuring in privacy, which is another advantage of braless measuring. The measurements you get without a bra are your most accurate baseline for finding properly fitting bras across all brands and styles.

Using a bra size calculator is simple and accurate when you input correct measurements. First, measure your underbust (band) and bust (fullest part) in either inches or centimeters. Enter both measurements into the calculator along with your preferred sizing method (UK or US). The calculator automatically determines your band size by rounding your underbust to the nearest even number, then calculates cup size by finding the difference between your bust and band measurements. For example, if you measure 34 inches underbust and 38 inches bust, the calculator determines: Band = 34 (already even), Cup difference = 38 - 34 = 4 inches = D cup, Final size = 34D. Most calculators also provide sister sizes (alternative sizes with the same cup volume) for when your exact size is unavailable. The calculator on this page accounts for both UK and US sizing methods, allows inch or centimeter inputs, and provides detailed explanations of your results including sister sizing options.

Band size and cup size are two separate measurements that work together to determine your complete bra size. Band size is the number (32, 34, 36, 38, etc.) representing the circumference around your ribcage directly under your breasts where the bra band sits. This measurement determines how tight or loose the bra feels around your body and provides 80% of the bra's support. Cup size is the letter (A, B, C, D, DD, etc.) representing the volume of your breast tissue, calculated by the difference between your bust measurement and band size. Cup sizes are relative to band size - a D cup on a 32 band is smaller in volume than a D cup on a 38 band. To measure band size, wrap a tape measure under your bust snugly. To determine cup size, measure around the fullest part of your bust, then subtract your band measurement. Each inch of difference represents one cup size. Both measurements are equally important for finding a bra that fits correctly with proper support and comfort.

You can measure in either inches or centimeters depending on what's more familiar to you and what sizing system your preferred brands use. For inches (used in US and UK sizing): measure your underbust and bust, then use those inch measurements directly in the calculator or sizing charts. For centimeters (used in EU sizing): measure both locations in cm, then either convert to inches (divide by 2.54) or use European sizing charts that work directly with cm measurements. Most online calculators accept both units. If you measure in cm and want US/UK sizing, simply divide your measurements by 2.54 to convert. For example, 86 cm underbust ÷ 2.54 = 34 inches. European sizes use your actual cm measurement as the band size (like 70, 75, 80) with the same letter cup sizes. Whether you measure in inches or centimeters, the resulting bra size should fit the same - it's just a different numbering system. Use whichever measurement unit your measuring tape displays and matches the sizing charts of brands you prefer.

Men measure breast size the same way as women - by measuring underbust (chest circumference below breast tissue) and bust (fullest part across breast tissue or pectoral muscles). For men with gynecomastia (enlarged breast tissue), these measurements determine the size needed for compression garments, support bras, or medical garments. Measure underbust where a band would sit, typically 36-48 inches for most men due to broader ribcages. Measure bust at the fullest projection of chest tissue. Subtract underbust from bust to determine cup size. Men commonly measure in the 38-46 band range with A-D cups for gynecomastia support. For transgender individuals or those using breast forms, measure with forms in place to determine desired size. Compression garments for gynecomastia often use S/M/L sizing instead of band/cup, but knowing your measurements helps select the correct size. Many men with gynecomastia benefit from medical-grade compression shirts designed specifically for male anatomy. For detailed guidance, visit our specialized breast size calculator for men.

If your measurements fall between two sizes, try both and let comfort guide your choice. If you're between band sizes (like measuring 33 inches), you can wear either a 32 or 34 band - choose 32 for firmer support and 34 for more comfort. If you're between cup sizes, consider the bra style: sized down for push-ups or padded bras (which add volume), size up for unlined or wireless bras (which don't add volume). Remember sister sizing: if 34C feels too loose in the band, try 32D (tighter band, same cup volume). If 34C feels too tight, try 36B (looser band, same cup volume). Band size is more critical than cup size for support, so prioritize getting the band right. When ordering online, some retailers offer free returns, letting you order multiple sizes to try at home. Your measurements might also change throughout your menstrual cycle, during pregnancy, or with weight fluctuations, so having bras in two close sizes provides options for different times of the month.

Different countries use different bra sizing systems, but your measurements remain the same - only the numbers change. UK sizing uses your actual underbust measurement as the band (32, 34, 36). US sizing adds 4-5 inches to underbust (so a 32 UK = 36-37 US band). European sizing uses centimeters directly (70, 75, 80 cm). French sizing adds 15 to the European size (80 EU = 95 FR). Australian sizing follows UK sizing. Cup letters are mostly consistent internationally, though some differences exist in larger sizes (UK DD = US DD, but UK E = US DDD/F). To convert between systems, start with your measurements in inches or cm. For UK/AU: use underbust rounded to even number. For US: add 4-5 to underbust. For EU: use underbust in cm. For FR: add 15 to EU size. The best approach is to measure yourself, then consult each brand's specific sizing chart rather than trying to convert between systems, as brands often have unique fit characteristics regardless of country standards.

Remeasure your bra size every 6-12 months as a routine check, and immediately after any significant body changes. Weight fluctuation of 10+ pounds can change both band and cup size. Pregnancy and breastfeeding cause dramatic size changes - measure each trimester during pregnancy and monthly while nursing. Starting or stopping hormonal birth control, hormone replacement therapy, or other medications affecting hormones can change breast size within weeks. Menopause often causes size changes. Fitness routines, especially strength training affecting pectoral muscles, can alter measurements. Age naturally changes breast tissue composition and size. If your current bras feel uncomfortable, leave marks, ride up, cause spillage, or have loose cups, measure immediately - your size has likely changed. Keep in mind that breast size can fluctuate 1-2 inches during your menstrual cycle, so measure mid-cycle for your most consistent baseline size. Maintaining accurately fitting bras prevents health issues like back pain, poor posture, and tissue damage over time.

If you don't have a fabric measuring tape, you can use alternative methods, though they're less accurate. Use a piece of non-stretchy string, ribbon, or even a shoelace to wrap around your underbust and bust. Mark or hold where the string completes the circle, then measure that length against a ruler, yardstick, or the edge of a piece of standard printer paper (which is 11 inches long). Another option is using a belt - wrap it around your body at each measurement point, mark the spot, then measure the belt length flat. You can also try on bras at a store to find your size empirically, trying different band and cup combinations until you find the best fit. However, the most practical solution is purchasing a fabric measuring tape - they cost under five dollars at craft stores, sewing shops, pharmacies, or online retailers like Amazon. Many stores also offer free measuring tapes if you ask at the customer service desk. Once you have a proper measuring tape, you'll get much more accurate and consistent measurements for all your bra shopping needs.

Bra sizing isn't standardized across brands, leading to significant size variations even when labels match. Different manufacturers use different sizing methodologies (UK vs US systems), varying fabric stretch and elasticity, different cup shapes and depths, inconsistent quality control, and unique fit models. For example, Victoria's Secret uses US sizing with their own variations, Marks & Spencer uses UK sizing but skips certain cup sizes (FF, HH), and European brands use completely different numbering. Additionally, bra style affects fit - a 34C balconette fits differently than a 34C plunge or sports bra even within the same brand. The cut, padding, underwire placement, and fabric all influence how a size fits. This is why reading reviews about fit, checking brand-specific sizing charts, and understanding each brand's methodology helps you shop successfully across multiple retailers. Many people find they wear 32D in one brand, 34C in another, and 32DD in a third - all offering similar fit due to style and manufacturing differences. When switching brands, always check their sizing guide and consider ordering multiple sizes for home try-on if possible.