Bra Size Calculator
Find your perfect fit instantly ⥠100% free, fast, trusted sizing đ¯
Try it now đ
Find your perfect fit instantly ⥠100% free, fast, trusted sizing đ¯
Try it now đ
A bra size calculator is a measurement-based tool that helps determine your correct bra size using your band measurement and bust measurement. Instead of guessing your size or relying on inconsistent brand labels, this calculator uses a structured formula to estimate your accurate band size and cup size. The result is expressed in a format such as 34B, 36C, or 32DD, where the number represents the band size and the letter represents the cup volume.
Many people wear the wrong bra size without realizing it. Common issues include straps digging into the shoulders, gaps in the cups, underwire discomfort, or a band that rides up in the back. These problems are usually caused by incorrect sizing. A bra size calculator eliminates guesswork by using your actual body measurements in inches or centimeters to calculate a size that provides better support, comfort, and fit. It is especially useful when buying bras online, trying a new brand, or after body changes such as weight gain, weight loss, or pregnancy.
The calculator works by using two primary measurements: the band measurement and the bust measurement. First, measure snugly around your ribcage, just under your breasts. This is your band measurement. Second, measure around the fullest part of your bust while keeping the measuring tape level. This is your bust measurement. For best results, stand straight and avoid pulling the tape too tight.
Step one is determining the band size. If you measure in inches, round your underbust measurement to the nearest whole number. In many sizing systems, if the number is even, that is your band size; if it is odd, you round up to the next even number. For example, if your underbust measurement is 31 inches, you typically round up to 32. This becomes your band size.
Step two is calculating the cup size. Subtract the band measurement from the bust measurement. The difference determines the cup letter. For example, if your bust measures 36 inches and your band size is 32 inches, the difference is 4 inches. A 1-inch difference usually corresponds to an A cup, 2 inches to B, 3 inches to C, 4 inches to D, 5 inches to DD, and so on. In this example, a 4-inch difference means a D cup, resulting in a calculated size of 32D.
A bra size calculator is useful in several real-life situations. If you are shopping for bras online and cannot try them on physically, using accurate body measurements ensures you select the closest possible size. This reduces returns and increases the chances of a comfortable fit.
It is also helpful after body changes. For example, weight fluctuations, pregnancy, breastfeeding, or fitness training can significantly affect breast volume and band measurement. A person who previously wore 34C may find that after weight loss their new measurement suggests 32D. Even though the cup letter changes, the overall breast volume may remain similar due to sister sizing.
Teenagers buying their first bra, individuals experiencing discomfort with their current bras, and anyone switching to sports bras or supportive undergarments can benefit from recalculating their size. Proper bra sizing improves posture, enhances comfort during daily activities, and provides better support during exercise.
The core formula behind the calculator is based on measurement difference. The basic structure can be written as: Cup Size = Bust Measurement â Band Measurement. The result of this subtraction determines the cup letter using a standardized difference scale. This logical approach ensures consistency across calculations.
Band Size = Rounded Underbust Measurement. If measuring in centimeters, the value is typically converted into inches or matched to the nearest standardized band size such as 70, 75, 80 in some international systems. The calculator may also adjust based on regional sizing charts such as US, UK, or EU formats.
Sister sizing is another concept included in advanced logic. Sister sizes are alternative sizes with similar cup volume but different band numbers. For example, 34C and 32D can have similar cup capacity because when the band decreases, the cup letter increases to maintain volume. Understanding this relationship helps users fine-tune their fit if the band feels too tight or too loose while the cup fits correctly.
Is the Bra Size Calculator accurate?
Yes. The calculator uses structured measurement formulas and standardized cup-difference logic to estimate a precise size. Accuracy depends on correct measuring technique and proper rounding of values.
Is this Bra Size Calculator free to use?
Yes. The tool is completely free and requires no registration. You can calculate your bra size instantly using your measurements.
Can I calculate bra size in centimeters?
Yes. The calculator supports both inches and centimeters. Measurements are converted internally to match the selected sizing system.
Does bra size vary by brand?
Yes. While the calculated size provides a strong starting point, some brands may fit slightly differently. Trying sister sizes can help if the initial fit feels slightly off.
Is my personal data stored?
No. All calculations are processed directly in your browser. No body measurements or personal information are saved or tracked.