Bra Size Calculator

How to use Bra Size Calculator (Step-by-Step)

Find your perfect bra size in seconds with our easy-to-use Bra Size Calculator. This tool helps you calculate your accurate bra size based on your band size (the measurement under your bust) and bust size (the measurement around the fullest part of your chest).

Our calculator provides instant results for multiple sizing systems, including US, UK, EU, FR, JP, and AU, making it simple to find your exact fit no matter where you shop.

Select your unit (cm or inches), choose your country, enter your band and bust measurements, and click Calculate to determine your actual bra size.

What Our Bra Size Calculator Does

Our Bra Size Calculator is designed to make sizing simple and accurate. Instead of guessing or relying on old measurements, you can enter your band and bust size to get an instant result that matches your body's current shape.

This helps you find your perfect fit, whether you're shopping locally or from international brands. By removing confusion between different size charts, it helps you confidently find your bra size and choose bras that feel comfortable, supportive, and right for you.

How to Measure Bra Size with Bra Size Calculator (Step-by-Step)

Here's a simple step-by-step guide to measure your bra size accurately using our Bra Size Calculator. Just follow each step to get your perfect fit in seconds.

Get ready

Wear a lightly lined, non-padded bra. Stand tall, relax your arms, and grab a soft measuring tape.

Set up the bra size calculator

Open the Bra Size Calculator, select CM or IN, and then choose your country's sizing system (US, UK, EU, FR, JP, AU).

Measure your band (underbust)

Place the tape directly under your bust, level around your ribcage. Pull it snug, not tight. Record to the nearest ¼ inch or 0.5 cm. Enter/select this as Band Size.

Measure your bust (overbust)

Wrap the tape around the fullest part of your chest, level across your back. The tape should lie flat without squeezing. Record to the nearest ¼ inch or 0.5 cm and enter as Bust Size.

Calculate

Tap Calculate to find your bra size. You'll see your band + cup size in your chosen country's system. You'll also see a breakdown of your band size, cup size, and country sizing system. Below your result, the tool displays sister sizes such as 38D and 42B, which have the same cup volume but different band sizes. You can try these if your current band feels too tight or too loose. Finally, a "Calculate Again" button allows you to recheck your measurements.

Why Wearing the Right Bra Size Matters

Wearing the right bra size does more than just make your clothes look better; it helps you feel comfortable, confident, and supported throughout the day. A properly fitted bra can improve your posture, prevent shoulder or back pain, and boost your overall comfort level. Many women don't realize that small differences in size can have a big impact on how a bra fits and feels.

Better Posture and Support

A well-fitting bra provides the right level of support for your bust, helping you maintain a straight, natural posture. When your band and straps fit correctly, the weight of your bust is evenly distributed, reducing pressure on your shoulders and spine. This prevents slouching and keeps you comfortable whether you're at work, walking, or relaxing.

Prevents Pain and Discomfort

Wearing the wrong size can cause digging straps, tight bands, and skin irritation. Over time, it can even lead to back, neck, or shoulder pain. The right bra size eliminates these issues by offering the right balance of snugness and flexibility, firm enough to support but soft enough to stay comfortable all day long.

Improves Shape and Appearance

The right bra can make a noticeable difference in how your clothes fit. It enhances your natural shape, gives a smoother look under clothing, and prevents common issues like gaping cups or bulging seams. Whether you're wearing a T-shirt, dress, or formal outfit, a properly fitted bra helps everything sit perfectly.

Boosts Confidence

Comfort directly affects confidence. When your bra fits properly, you don't have to adjust it constantly or worry about visible lines or slipping straps. You stand taller, feel more at ease, and move freely without distraction, a simple change that makes you look and feel your best.

Extends the Life of Your Bras

A well-fitting bra experiences less stretching, slipping, or wear and tear. That means your bras last longer and maintain their shape and elasticity over time. Investing a few minutes to find your correct bra size can actually help you save money in the long run.

Bra Size Chart 

Not sure where your size falls? Use this quick-reference chart to find your band-and-cup size combination. For a full international size chart including US, UK, EU, FR, JP, and AU conversions, visit the complete bra size chart page.

Band sizes run across the top from 32 to 52. Cup sizes run down the side from A through H. Your bra size is the combination of the two, so a 38 band with a D cup is a 38D.

Note: DDD and E represent the same cup volume in most sizing systems. The letter used depends on the brand. If you are unsure which applies to your bra, refer to the full size chart for a complete brand-by-brand breakdown.

What Are Sister Sizes in Bras?

If you have ever struggled to find your exact bra size in a store or online, sister sizes are the solution most women never hear about. Understanding bra sister sizes can open up a whole new range of options that fit just as well as your actual size, sometimes even better.

Sister sizes are bra sizes that share the same cup volume but have different band sizes. When you go up one band size, the cup letter goes down one step to keep the volume equal. When you go down one band size, the cup letter goes up one step for the same reason.

For example, if your size is 34C, your sister sizes are 32D and 36B. All three hold exactly the same amount of breast tissue. The only difference is how the band fits around your body.

Why Sister Sizes Matter

Knowing your sister sizes is useful in three practical situations.

1. If your exact size is out of stock, a sister size gives you an alternative that fits the cup just as well. You just need to adjust the band feel slightly.
2. If your band feels right but the cup is slightly off, moving to a sister size fixes the cup without you having to size up or down completely.
3. Different brands cut their bras differently. A 34C from one brand may fit more like a 32D from another. Knowing your sister sizes helps you navigate this inconsistency without guessing.

How to Find Your Sister Sizes

Go up one band size and down one cup letter for a looser band feel. Go down one band size and up one cup letter for a firmer band feel. The cup volume stays the same either way. So if you are a 36D, your sister sizes are 34DD for a firmer fit and 38C for a looser fit.

Our bra size calculator automatically shows your sister sizes alongside your result so you always leave with more than one option to try.

Find the Right Bra for Your Breast Shape

Getting your bra size right is only half the equation. The other half is your breast shape. Two women can wear the exact same size and need completely different bras because of how and where their breast tissue sits. Once you know your shape, finding a bra that actually fits becomes much simpler.

Here are the six most common breast shapes and the bra types that work best for each.

Full on Top

Full on top breasts carry more volume above the nipple line than below. The most common fitting problem with this shape is spillage at the top of the cup, which happens when the cup style is too shallow to contain the tissue sitting higher on the chest.

Best bra types: Full coverage bras and balconette styles work well here. Look for cups with a higher cut at the top, and avoid demi or half-cup styles, as they tend to cut across the fullest part of the breast.

Full on Bottom

Full on bottom breasts carry most of their volume below the nipple line with a softer, lighter upper area. Cups designed with equal depth all the way around often gap at the top in this shape.

Best bra types: Balconette and plunge bras are ideal as they support the lower breast volume without leaving empty space at the top. T-shirt bras with molded cups also work well for everyday wear.

East West

East-west breasts sit wide on the chest with nipples that point outward rather than forward. The main challenge with this shape is creating a centered, supported look without the breasts sitting too far apart.

Best bra types: Plunge bras are the most effective style here as the narrow center panel draws tissue inward. Push-up bras and styles with side support panels also help redirect tissue toward the center.

Side Set

Side set breasts are similar to east-west in that they sit wide apart on the chest, but the nipples point more forward rather than outward. There is usually a noticeable gap between the breasts even when wearing a bra.

Best bra types: Plunge bras and push-up styles with side support work well for this shape. Look for bras with a narrow gore, which is the panel between the cups, as a wider gore will increase the gap rather than reduce it.

Teardrop

Teardrop breasts are rounded and fuller at the bottom with a gradual slope toward the top. This is one of the most common breast shapes and one of the most versatile for bra fit.

Best bra types: Most bra styles work well with a teardrop shape. Plunge bras enhance the natural shape nicely, while T-shirt bras provide a smooth, seamless look under clothing. Full coverage styles also fit this shape without gaping.

Athletic

Athletic breasts tend to be wider at the base, firmer, and have less soft tissue overall. Because the tissue sits close to the chest wall, standard molded cups can lift away at the top and create an unflattering gap.

Best bra types: Sports bras are the obvious choice and genuinely work well for this shape during activity. For everyday wear, plunge bras and push-up styles with angled padding help add volume and keep the cup sitting flush against the breast rather than lifting away.

Not sure which shape applies to you? The easiest way to identify your breast shape is to stand in front of a mirror without a bra and notice where most of the tissue sits relative to your nipple line, how much space there is between your breasts, and which direction your nipples face. Most women are a combination of two shapes rather than a perfect match for just one, so focus on the characteristic that causes the most fitting challenges for you.

Common Bra Fitting Mistakes and Their Solutions

Even with the right measurements, small fitting mistakes can make a bra feel uncomfortable all day. Here are the most common problems women experience and exactly how to fix them.

Band Rides Up at the Back

If your bra band creeps up toward your shoulder blades throughout the day, your band size is too loose. A correctly fitted band should sit horizontally around your body and stay in place without moving.

How to fix it: Go down one band size and up one cup size. For example, swap a 36C for a 34D. The cup volume stays the same, but the band fits more securely.

Straps Dig Into Your Shoulders

Straps that leave marks or cause shoulder pain are not actually a strap problem. They are a band problem. When the band is too loose, it cannot support your bust properly, so the straps overcompensate by taking on more weight than they were meant to carry.

How to fix it: Go down one band size so the band does its job. Straps should carry no more than 20% of your support. Once the band fits, the strap pressure will reduce on its own.

Cups Overflow or Spill at the Top

If breast tissue is spilling over the top or sides of your cups, your cup size is too small. This is one of the most common fitting mistakes and one of the easiest to correct.

How to fix it: Go up one cup size, for example, from a 34C to a 34D. If spillage is happening at the sides rather than the top, the cup shape may not suit your breast shape, rather than the size being wrong.

Underwire Pokes or Digs In

Underwire should sit flat against your ribcage and fully surround your breast tissue without pressing into it. If the wire pokes into the side of your breast or digs into your chest, the cup is either too small or the wrong shape for your body.

How to fix it: Go up one cup size and look for a deeper cup style, such as a full-coverage or plunge style. These styles are designed for more projected breast shapes and allow the wire to sit in the correct position.

Cup Gap or Wrinkle at the Top

An empty fabric at the top of the cup means your cup size is too large or the style is not the right match for your breast shape. Gaping cups not only look unflattering but also mean you are not getting the support the bra was designed to provide.

How to fix it: Go down one cup size. If gaping continues after sizing down, try a molded cup style. Molded cups hold their shape independently and sit flush against the body without creating gaps.

Straps Keep Falling Off Your Shoulders

Straps that slide off constantly are usually a sign that the band is too loose rather than a problem with the straps themselves. When the band sits too high at the back, it changes the angle of the straps, and they lose their grip on your shoulders.

How to fix it: Go down one band size first before adjusting the straps. If the problem continues, a racerback-style bra may help, as the center placement on the back keeps the straps secure on narrow or sloped shoulders.

International Bra Size Conversion Chart

The International Bra Size Conversion Chart helps you compare your bra size across different countries. Since every region uses its own sizing system, this table makes it easy to match your size in US, UK, EU, FR, JP, and AU measurements. It's a quick way to find your perfect fit when shopping for bras from international brands.

International Cup Size Conversion Chart in inches and CM

The International Cup Size Conversion Chart helps you compare your cup size in different countries. Your cup size is based on the difference between your bust and band measurements. The tables below show how that difference changes your cup size in US, UK, EU, FR, JP, and AU sizing systems, first in inches and then in centimeters. These charts make it easier to understand what your measurements mean and to find the right fit when shopping for bras from anywhere in the world.

International Cup Size Conversion Chart In Inches

International Cup Size Conversion Chart In Centimeters

Why Use Our Bra Size Calculator

Finding your correct bra size should be simple and stress-free. Our Bra Size Calculator provides quick, accurate results, making bra shopping easier and more reliable.

Fast and Accurate Results

Just enter your bust and band measurements, and the calculator will instantly show your correct size without any manual calculations.

Works for All Countries

Whether you shop from the United States, the United Kingdom, Europe, France, Japan, or Australia, the tool automatically converts your measurements to match international sizing standards.

Data Privacy Ensured

Your measurements are not stored or shared. Everything you enter stays private and secure.

Free and Mobile Friendly

The tool is free to use and works smoothly on mobile, tablet, and desktop devices without requiring downloads or registration.

Popular Bra Size Guides

32A Bra Size | 32B Bra Size

32C Bra Size | 32D Bra Size

34A Bra Size | 34B Bra Size

34C Bra Size | 34D Bra Size

36A Bra Size | 36B Bra Size

36C Bra Size | 36D Bra Size

38A Bra Size | 38B Bra Size 

38C Bra Size | 38D Bra Size 

40A Bra Size | 40B Bra Size 

40C Bra Size | 40D Bra Size 

42A Bra Size | 42B Bra Size 

42C Bra Size | 42D Bra Size 

Popular Bra Types Guides

Bralette Bra | Push-Up Bra

T-Shirt Bra | Sports Bra

Strapless Bra | Balconette Bra