Bra Fit Calculator

👤

Reviewed by Sarah Jenkins, Professional Fit Specialist

Verified for accuracy in sizing standards and fitting methodology.

Finding the perfect bra size is essential for comfort and support. Our bra fit calculator uses professional sizing algorithms to help you determine your band and cup size based on your unique body measurements.

Bra Fit Calculator

Measure snugly around your ribcage, directly under your bust.

Measure around the fullest part of your chest.

Calculation Breakdown

Bra Fit Calculator Formula

Band Size = Underbust + 4 (if even) or + 5 (if odd)

Cup Size = Bust – Calculated Band Size

Source: Real Simple Fitting Standards

Variables:

• Underbust: The circumference of your ribcage just below the breast tissue.
• Bust: The circumference of the chest at the fullest point of the breasts.
• Band Size: The numerical part of your bra size (e.g., 32, 34, 36).
• Cup Size: The letter part of your bra size (e.g., A, B, C, D) determined by the difference between bust and band.

Related Calculators

• Bra Size Converter (US to UK)
• Breast Shape Identification Guide
• Sister Size Chart Tool
• Maternity Bra Fitting Calculator

What is Bra Fit Calculator?

A bra fit calculator is a digital tool designed to translate physical body measurements into industry-standard bra sizes. Because bra manufacturing isn’t globally uniform, this tool provides a baseline starting point based on the most common US/UK sizing systems.

Using a calculator ensures that your band provides 80% of the support while the cups contain the breast tissue comfortably without spilling or gaping, which is critical for long-term spinal health and posture.

How to Calculate Bra Size (Example)

1. Measure Underbust: Say your underbust is 30 inches. Since it is even, add 4. Band = 34.
2. Measure Bust: Say your bust is 37 inches.
3. Subtract: 37 (Bust) – 34 (Band) = 3 inches.
4. Find Cup: A difference of 3 inches corresponds to a “C” cup. Your size is 34C.

Frequently Asked Questions (FAQ)

How often should I use a bra fit calculator? You should measure yourself every 6 months or after significant weight changes, as breast tissue density changes over time.

Why is my calculated size different from my current bra? Different brands use different patterns. The calculator provides a “starting size” for you to try on.

What if my bust measurement is between inches? Always round up to the nearest whole number to ensure the cup isn’t too restrictive.

Does the bra fit calculator work for sports bras? Yes, although some sports bras use S/M/L sizing, knowing your cup/band helps in selecting high-impact gear.