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Bra Size Calculator
Enter your underbust and bust measurements to estimate your correct US band and cup size.
Bra Size Estimator
Measure snugly around your ribcage, directly underneath your breasts.
Measure loosely around the fullest part of your bust while standing straight.
Understanding Bra Sizing
A well-fitting bra is essential for comfort and support, yet finding the correct size can often feel confusing. Standard US bra sizing relies on two primary measurements: the band size (your ribcage) and the cup size (the fullest part of your bust).
How to Measure Properly
- The Underbust (Band Size): Measure snugly directly under your breasts, where the band of a bra would naturally sit. Keep the measuring tape parallel to the floor.
- The Bust (Cup Size): Measure loosely around the fullest part of your breasts, keeping the tape level.
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.