Bra Size Calculator Online – Find Your Perfect Fit

Studies suggest that a large percentage of women are wearing the wrong bra size without even knowing it, and the consequences go beyond discomfort — poor fit can affect posture, cause back pain, and make even well-fitting clothes look off. The Bra Size Calculator takes the uncertainty out of the process entirely. Enter your underbust and bust measurements, choose whether you are working in centimeters or inches, and receive your accurate bra size — including band size and cup size — in seconds. No guessing, no confusing size charts to decode manually, and no trip to a fitting room required.

How to Measure Before You Calculate

Getting accurate results starts with taking the right measurements. Here is how to do both correctly:

Underbust: Wrap a measuring tape directly under your bust, right where the band of a bra would sit. Keep the tape snug against your body and level all the way around — not too tight, not loose enough to slip.

Bust: Measure around the fullest part of your chest, keeping the tape relaxed rather than pulled tight. Make sure it stays parallel to the ground and does not dip at the back.

How to Use the Bra Size Calculator

Once you have your measurements, the rest is straightforward:

Select Your Unit: Choose centimeters or inches from the dropdown depending on which unit your measuring tape uses. The calculator works accurately with both and there is no need to convert anything yourself.

Enter Your Underbust Measurement: Type in the number you recorded from your underbust measurement. This figure is what determines your band size — the numeric part of your bra size such as 32, 34, or 36.

Enter Your Bust Measurement: Add your bust measurement in the same unit. The difference between this number and your underbust measurement is what determines your cup size — the letter part of your bra size such as A, B, C, or D.

Click Calculate Bra Size: Your complete result appears immediately on a styled card showing your full bra size (for example 34B or 75C), along with an explanation of what the size means. The breakdown table below covers every step — your unit, both measurements, the difference between them, the band size, the cup size, and the final result all laid out clearly.

Why Use the Bra Size Calculator Online?

Takes the Guesswork Out of Sizing: Most people estimate their bra size based on what they have always bought, which is not always accurate — especially after weight changes, pregnancy, or simply years of wearing the wrong size out of habit. Two measurements and a click gives you a result grounded in your actual current measurements.

Works in Both Metric and Imperial: Whether your tape measure shows centimeters or inches, the calculator handles both without asking you to do any conversion in advance. Just enter the numbers as they appear on your tape and the calculator takes care of the rest.

Full Breakdown Included: The results do not just show a size — they walk you through the band calculation, the cup difference, and how those two figures combined to produce your final size. Understanding the logic behind your size is genuinely useful when shopping across different brands or sizing systems.

Measurement Guidance Built In: The calculator includes clear instructions for taking both measurements correctly right on the page. If you have never measured yourself before or want to double-check your technique, the guidance is right there without needing to look anything up elsewhere.

Free, Private, and Instant: Your measurements stay with you — nothing is stored or submitted anywhere. The calculator is completely free, requires no account, and works on any device the moment you open it.