Bra size Calculator

Finding the right bra size isn’t always as straightforward as it seems. A bra can feel too tight, too loose, or simply uncomfortable even when you think you’ve chosen the right size.

Our free Bra Size Calculator makes it easier. All you need are two measurements: your underbust measurement and your bust measurement. Enter them into the calculator to get an estimated bra size.

What Is a Bra Size Calculator?

A bra size calculator uses your body measurements to estimate the bra size that may fit you best.

A typical bra size has two parts:

• Band size: the number, such as 32, 34, or 36

• Cup size: the letter, such as A, B, C, or D

For example, 34C has a band size of 34 and a C cup.

Keep in mind that bra sizing isn’t exactly the same everywhere. Different brands and countries can use slightly different sizing systems, so your calculated size is best used as a starting point.

How to Use the Bra Size Calculator

Using the calculator is simple. You’ll need to know:

1. Your underbust measurement

2. Your bust measurement

Enter both measurements, choose the correct unit, and the calculator will estimate your bra size.

The accuracy of the result depends on how accurately you measure, so it’s worth taking a little extra care with the measurements.

How to Measure Your Bra Size

You don’t need anything complicated. A flexible measuring tape and a mirror are enough.

1. Measure Your Underbust

Wrap the measuring tape around your body directly underneath your bust.

Keep the tape:

• Snug, but not painfully tight

• Straight and level around your body

• Flat against your skin

• Free from twisting

Stand normally while taking the measurement and note the result in inches or centimeters.

This measurement is used to determine your band size.

2. Measure Your Bust

Next, measure around the fullest part of your bust.

The tape should be comfortable rather than tight. Keep it level across your back and make sure it isn’t pressing into your body.

Try to stand naturally while measuring. Take the measurement once or twice to make sure you get a consistent number.

How Is Bra Size Calculated?

One common way to estimate cup size is to compare your bust measurement with your band size.

The basic calculation is:

Bust measurement − band size = cup difference

For example, suppose your underbust measurement is 31 inches and your bust measurement is 36 inches.

The 31-inch underbust may be rounded to a 32 band size.

Then:

36 − 32 = 4 inches

Using a standard US sizing guide, a 4-inch difference corresponds to a D cup.

That gives an estimated size of 32D.

You don’t have to do the calculation yourself — the calculator does it for you.

Bra Cup Size Chart

A commonly used US cup-size guide looks like this:

This is a general guide. Cup sizing can vary between brands and sizing systems, so don’t be surprised if a manufacturer’s chart gives you a slightly different result.

Bra Size Chart

Here are some common US bra sizes:

Use this as a general reference rather than a universal chart. The same labeled size can fit differently depending on the brand and style.

What Do the Number and Letter Mean?

The number and letter in a bra size tell you different things.

What does the number mean?

The number is the band size. It relates to the measurement around your rib cage, underneath your bust.

So, in 34C, the 34 refers to the band.

What does the letter mean?

The letter represents the cup size. It’s based on the difference between the bust measurement and the band size.

One thing that’s easy to misunderstand is that a cup letter doesn’t represent one fixed size. A C cup, for example, can have a different volume depending on the band size.

Common Bra Measuring Mistakes

A small mistake when measuring can change the result. Here are a few things to watch out for.

Measuring over a padded bra

Padding can add to your bust measurement. If possible, measure without a padded bra or wear a thin, non-padded bra.

Pulling the tape too tight

The tape should sit against your body without squeezing it. Pulling it too tightly can give you a smaller measurement than you actually need.

Letting the tape move

Make sure the tape stays level all the way around your body. If it slopes up or down, the measurement may not be accurate.

Using an old bra size

Your size can change over time, so don’t rely only on the size you bought a few years ago. Taking fresh measurements is usually a better starting point.

Measuring only once

If you’re unsure about a measurement, take it again. If you get roughly the same number each time, you’re probably measuring consistently.

Signs Your Bra May Not Fit Properly

Your calculated size is only an estimate. The real test is how the bra feels and fits.

Some signs that the size or style may not be right include:

• The band rides up your back.

• The straps dig into your shoulders.

• The cups have large gaps.

• Breast tissue spills over the top or sides.

• The band feels uncomfortably tight.

• The underwire doesn’t sit comfortably.

If you’re seeing any of these problems, check your measurements again and compare them with the size chart provided by the brand you’re buying from.

Is a 32D Bigger Than a 34D?

Bra sizing isn’t quite that simple.

The 32 and 34 refer to different band sizes, while D refers to the cup size within that sizing system. Cup volume changes as the band size changes, so a D cup doesn’t have exactly the same volume across every band size.

That’s also why sister sizes can sometimes be useful when you’re between sizes.

Is 34C Bigger Than 32C?

The band sizes are different, so the two bras aren’t identical in overall fit or cup volume.

Even though both have a C cup, 34C is designed for a larger band than 32C. This is another reason it’s better to look at the complete bra size rather than the cup letter by itself.

How Accurate Is an Online Bra Size Calculator?

A bra size calculator can give you a useful starting point, but it can’t guarantee the perfect fit for every bra.

That’s because brands can use different sizing systems, and two bras with the same labeled size can fit differently depending on their design.

For a better result:

1. Take your measurements carefully.

2. Use the calculator to get an estimated size.

3. Check the brand’s own size chart before buying.

4. Pay attention to how the bra actually fits.

Frequently Asked Questions (FAQs)

How do I calculate my bra size?

Measure around your rib cage underneath your bust and around the fullest part of your bust. Use the difference between these measurements to estimate your cup size and combine it with your band size.

What is the easiest way to find my bra size?

Using a measuring tape and a bra size calculator is one of the simplest ways to get an estimate. You’ll need your underbust and bust measurements.

What does 34C mean?

In a 34C bra size, 34 refers to the band size and C refers to the cup size.

Is cup size based on bust measurement?

Not on bust measurement alone. Cup size is generally determined by comparing the bust measurement with the band measurement.

Should I measure my bra size while wearing a bra?

It’s best to avoid thick or padded bras because they can affect your measurement. If you wear a bra while measuring, a thin, non-padded bra is usually a better option.

Can my bra size change?

Yes. Your measurements can change over time because of changes in weight, body composition, pregnancy, breastfeeding, hormonal changes, and other factors. If your current bras no longer fit the way they used to, taking new measurements can help.