Bra Size Calculator

Instantly find your accurate bra size with our easy-to-use Bra Size Calculator. Follow our simple steps for a perfect fit.

Find Your Perfect Fit

Your Results

Band Size

Cup Size

Cup Volume

Your bra size is calculated by determining your band size from your underbust measurement and your cup size from the difference between your bust and band measurements.

Sister Size Chart

Sister sizes have the same cup volume. If your band feels too tight or loose, you can try a sister size.

Band Down	Your Size	Band Up

What is a Bra Size Calculator?

A Bra Size Calculator is an online tool designed to help you determine your correct bra size based on your body measurements. Finding the right bra size is crucial for comfort, support, and overall breast health. Many people wear the wrong bra size, which can lead to issues like back pain, strap slippage, and discomfort. Our Bra Size Calculator simplifies the process, giving you a reliable starting point for finding the perfect fit. This tool is for anyone who wears a bra and wants to ensure they are wearing the correct size. A common misconception is that bra sizes are static; however, your size can change over time due to factors like weight fluctuation, hormonal changes, and aging, so it’s a good idea to use a Bra Size Calculator periodically.

Bra Size Calculator Formula and Mathematical Explanation

The calculation for bra size involves two key measurements: the underbust and the bust. The Bra Size Calculator uses a standard formula to convert these measurements into a bra size.

1. Determine Your Band Size: Your band size is based on your underbust measurement. A common method is to measure your ribcage just under your bust, round to the nearest whole number, and then if the number is even, add 4 inches, or if it’s odd, add 5 inches. This is your band size.
2. Determine Your Cup Size: Your cup size is the difference between your bust measurement and your calculated band size. Each inch of difference corresponds to a letter. For example, if the difference is 1 inch, you are an ‘A’ cup; 2 inches, a ‘B’ cup; and so on.

Variable	Meaning	Unit	Typical Range
Underbust	Measurement around the ribcage directly under the bust.	inches or cm	26 – 48 inches
Bust	Measurement around the fullest part of the bust.	inches or cm	30 – 55 inches
Band Size	The numerical part of your bra size.	inches	30 – 52
Cup Size	The letter part of your bra size, determined by the bust-band difference.	letter (A, B, C…)	AA – H

Practical Examples (Real-World Use Cases)

Here are a couple of examples to illustrate how our Bra Size Calculator works:

Example 1:

• Underbust Measurement: 31 inches
• Bust Measurement: 36 inches
• Band Size Calculation: 31 (odd) + 5 = 36. Her band size is 36.
• Cup Size Calculation: 36 (bust) – 36 (band) = 0. This suggests a cup size smaller than A, possibly AA.
• Resulting Bra Size: 36AA

Example 2:

• Underbust Measurement: 34 inches
• Bust Measurement: 39 inches
• Band Size Calculation: 34 (even) + 4 = 38. Her band size is 38.
• Cup Size Calculation: 39 (bust) – 38 (band) = 1 inch. This corresponds to an ‘A’ cup.
• Resulting Bra Size: 38A

How to Use This Bra Size Calculator

Our Bra Size Calculator is designed for ease of use. Follow these simple steps to find your size:

1. Enter Your Measurements: Input your underbust and bust measurements into the designated fields.
2. Select Your Unit: Choose whether your measurements are in inches or centimeters.
3. Calculate: Click the “Calculate” button to see your results.
4. Review Your Results: The calculator will display your calculated band size, cup size, and full bra size. You’ll also see a chart of sister sizes.
5. Decision-Making: Use this size as a starting point when shopping for bras. Remember that fit can vary by brand and style, so it’s always a good idea to try bras on.

Key Factors That Affect Bra Size Results

Several factors can influence your bra size. It’s important to be aware of these when using a Bra Size Calculator.

• Weight Changes: Gaining or losing weight will likely change your bra size.
• Hormonal Fluctuations: Your menstrual cycle, pregnancy, and menopause can all affect breast size.
• Aging: As you age, skin elasticity and tissue density change, which can alter your bra size.
• Brand and Style: Bra sizing is not always consistent across different brands or even different styles from the same brand.
• Measurement Accuracy: Ensure you are measuring correctly. The tape should be snug but not tight.
• Time of Day: Your body can change slightly throughout the day, so it’s best to measure when you feel your body is at its baseline.

Frequently Asked Questions (FAQ)

How often should I measure my bra size?

It’s a good practice to re-measure your bra size every 6-12 months, or after any significant life changes like pregnancy or weight fluctuation. Using a Bra Size Calculator regularly can help you stay comfortable.

What are sister sizes?

Sister sizes are alternative bra sizes with the same cup volume. For instance, a 34C has the same cup volume as a 32D and a 36B. They can be helpful if your usual size isn’t available or doesn’t fit quite right in a particular style.

Why do my bra straps keep slipping off?

This is often a sign of a band that is too loose. The band should provide most of the support, not the straps. Try a smaller band size and a larger cup size (a sister size).

What if I’m between sizes?

If you’re between sizes, it’s often best to try both. You might find that one fits better in certain styles. Our Bra Size Calculator provides a great starting point, but personal comfort is key.

Should I use a padded or non-padded bra for measurements?

For the most accurate measurements, it’s best to wear a non-padded, non-minimizer bra, or no bra at all.

Does the +4/+5 inch method always work?

The +4/+5 inch method is a traditional approach. Some modern brands have moved away from it. If the calculated size doesn’t seem right, you can also try using your rounded underbust measurement as your band size and recalculate from there. The Bra Size Calculator is a guide, and adjustments may be needed.

How do I know if a bra fits correctly?

A well-fitting bra should have a snug band that sits horizontally across your back, cups that fully contain your breasts without spillage or gaps, and straps that don’t dig in.

Can I trust the results of an online Bra Size Calculator?

An online Bra Size Calculator is an excellent starting point and can be very accurate if you measure correctly. However, always consider it a guide and prioritize comfort and fit when trying on bras.