Bra Size Calculator

Estimate bra size from band (underbust) and full-bust measurements.

How the Math Works

The Bra Size Calculator uses standard measurement techniques to determine your size. First, measure your band size by wrapping a flexible tape measure snugly around your ribcage just under your bust, then round to the nearest even number. Next, measure your bust at the fullest point while standing straight. The band size is your underbust measurement, and your cup size is calculated by subtracting the band size from your bust measurement (e.g., a 4-inch difference equals a D cup). This process accounts for natural body proportions and adjusts for standard sizing conventions.

Practical Applications

To use this calculator, start by measuring your band size with a cloth tape measure around your ribcage under your bust, ensuring it’s level and not too tight. Then, measure your bust standing upright with your back against a wall, keeping the tape at the fullest part. Input these measurements into the calculator, which will automatically compute your band and cup size. For accuracy, measure when your breasts are in a natural position, and consider re-measuring if your weight fluctuates significantly. Remember that different brands may have slight variations in sizing, so consulting specific brand charts is always wise.

Day-to-Day Use

Knowing your accurate bra size enhances daily comfort and support, reducing strain on your back and shoulders that can come from ill-fitting bras. A properly fitted bra improves posture and provides better movement freedom during physical activities, while also boosting confidence through a comfortable, well-supporting garment. Regularly checking your size ensures your needs are met as your body changes over time, preventing issues like spillage, straps digging in, or excessive band riding up — all of which can detract from both comfort and self-assurance throughout your day.

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