Bra Size Calculator
Enter your underbust and bust measurements to estimate your correct US band and cup size.
Bra Size Calculator
Measure snugly around your ribcage, directly underneath your breasts.
Measure loosely around the fullest part of your bust while standing straight.
Accurate Bra Size Calculator: Find Your Perfect Fit
Studies show that up to 80% of women worldwide are wearing the incorrect bra size, leading to chronic back pain, poor posture, restricted breathing, and general daily discomfort. The Calculay Bra Size Calculator utilizes standardized measuring algorithms to help you determine your exact band and cup size, ensuring optimal support and anatomical health.
Why Correct Sizing is Crucial
A bra is not just an aesthetic garment; it is a structural support system. When the band is too loose, the weight of the breasts is improperly transferred entirely to the shoulder straps, causing deep shoulder grooves, neck tension, and tension headaches. When the cups are too small, the restrictive pressure can impede lymphatic drainage and cause painful tissue chafing.
A perfectly fitted bra should have 80% of the support coming directly from the band wrapping securely around the ribcage, with only 20% of the support relying on the shoulder straps.
How to Measure Yourself Accurately
To use our calculator, you will need a soft, flexible measuring tape. For the most accurate results, take these measurements while unbanded or while wearing a non-padded, everyday bra.
- Step 1 (The Band Size): Wrap the measuring tape snugly around your ribcage, directly directly beneath your bust where the bra band normally sits. Ensure the tape is perfectly horizontal. Round this number to the nearest whole inch or centimeter.
- Step 2 (The Bust Size): Wrap the measuring tape around the fullest part of your breasts (usually across the nipples). The tape should rest lightly, without compressing the breast tissue.
The Math Behind the "Plus 4" Method
This calculator uses the traditional US "Plus 4" fitting methodology.
- If your raw underbust measurement is an even number, we add 4 inches to calculate your final Band Size.
- If your raw underbust measurement is an odd number, we add 5 inches to find the next even Band Size.
- Your final Band Size is then subtracted from your Bust Measurement. Every 1-inch difference corresponds to exactly one cup size up (e.g., 1 inch difference = A, 2 inches difference = B, 3 inches difference = C).
Disclaimer: Sizing varies wildly between manufacturers and brands. Use this tool as a starting baseline estimate, but always verify fit in-store if possible.