Have you ever ordered a bra from us in your usual size and still felt that it didn´t fit you as expected? You are far from alone. The fact is that bra sizes are not always fully comparable between different brands, even if the size label looks the same.

At Miss Mary, the recommended size may sometimes differ from other brands or from what you are wearing right now. This is due to several factors and here we explain why, so that you can more easily find a bra that fits really well.

Different brands grade their sizes in different ways

It may sound strange, but a size is not always a “fixed number.” When a brand develops a bra, they start from a base size (e.g. 34C) and then grade up and down to other sizes. The problem? There are different ways to grade.

This means that two bras in the same size can differ, for example, in how:

• The cup is shaped (depth, width, height).

• The wire is shaped (narrower/wider).

• High or low the bra sits in the front or at the sides.

• Firm the band around the body is.

• The straps are placed.

So even if the same size is printed in two bras, they may be constructed in completely different ways and therefore feel like different sizes on the body.

Fit is about both measurements and shape

Many think that bra size is an exact measurement, but fit is also about how the breasts are shaped and how the bra is designed.

Two people can have the same band and cup size, but still need different models depending on whether:

• The breasts are more round or pointed in shape.

• You are fuller on the top or the bottom – all bodies are different!

• The volume sits more toward the center or toward the sides.

• You need support, separation, or lift.

We create bras with a focus on support, comfort and stable fit, which sometimes makes our models feel different compared to brands that make lighter or more fashion‑focused constructions.

The properties of the materials affect the size

Materials are one of the biggest reasons sizes can feel different between brands. Two bras can have the same size label, but if one is made of a firm and stable material and the other of something more elastic, they will fit completely differently.

Examples of what materials can affect:

• Elasticity: How much the band under the bust stretches.

• Stability: How well the bra keeps the breast in place throughout the day.

• How it feels against the skin: Some materials lose their shape faster, others last longer.

• How the cup shapes itself: Lace, mesh, microfiber and cotton behave very differently.

In other words: the size on the label is not always the whole truth. The material affects how the bra fits, and therefore you may sometimes need to adjust the size to get the same comfort and support.

The construction makes a big difference

Bra size depends on the entire construction.
Two bras can have the same size label but still fit differently depending on whether:

• The cup has or does not have an underwire.

• The model is full cup, balconette or T‑shirt bra.

• It is padded or unpadded.

• It has side support or extra reinforcements.

• It has a wider or narrower back.

We work with constructions that provide:

Comfortable support.
Comfortable fit all day.
Stability even in larger cup sizes.

This may mean that you sometimes need to go up or down in band and/or cup size compared to what you usually wear in other brands. Sometimes it can differ by several size steps.

Your “usual size” may also be wrong – without you knowing it

This is common, and nothing to be embarrassed about: many wear a bra that works okay but is not actually optimal in size.
Common signs that the size is not quite right:

• The band rides up in the back.

• The cup gaps or presses.

• The wire does not sit against the sternum.

• The straps slip or dig in.

• You need to adjust the bra several times during the day.

When you try a bra that is more stably constructed, you may suddenly notice a difference. Try using our size guide to find the right size more quickly.

How to find the right size at Miss Mary

To make it easy, we have created a size guide to help you find your perfect size.

The recommended size may vary from other brands or from what you wear now. This is because many brands grade their sizes and products in different ways. The properties of materials also play a crucial role and can vary greatly from brand to brand.

👉 Our best tip is to always start from our guide and measure yourself if you are unsure – especially if you haven't done it in a long time.

📏 Pull the measuring tape snugly when measuring under the bust where the band should sit tight. If you land between two measurements, choose the smaller one.

📏 When measuring around the bust itself, however, make sure not to pull too tightly because the breasts will be compressed. If you land between two cup sizes, choose the larger one.

A bra that fits right should feel good all day

When the size is right you often notice the difference immediately: better support, nicer shape, and above all more comfort. And remember: it is not you who “has the wrong size,” it’s simply that bra sizes are not universal between brands.

Want help finding the right size? Our size guide is a great first step and you are always welcome to contact us if you want personal advice.

Finally, a few words about the different sizing systems that exist and how you can think about them when trying to find the right size.

Why do bra sizes differ around the world?

It is confusing that the same bra size does not always mean the same thing in all countries because there are different sizing systems that measure and label bra sizes in different ways.

A bra size, however, always consists of the same two parts: the band size around the body under the bust and the cup size, which is based on the difference between the measurement around the fullest part of the bust and under the bust.
What differs is how these measurements are calculated and labeled.

Examples of different sizing systems

Here are some of the most common systems and the explanation for why the same size can look completely different on the label:

Europe (standard‑EU, e.g. Sweden, Germany, Poland, etc.)
Band size in centimeters + cup letter.
Example: EU 75C, EU 80D.
This is the system most Northern and Central European brands use.

Spain & France (and sometimes Belgium)
Also use centimeters but add 15 cm to the band measurement compared to the EU system + cup letter.
Example: FR/ES 90B ≈ EU 75B.
Belgium often follows the same system but also uses EU and UK.

United Kingdom (UK)
Band size in inches + cup letters.
Example: UK 34C ≈ EU 75C, UK 36DD ≈ EU 80E.
The UK traditionally uses the +4‑inch method: if the measurement is, for example, 30 inches, you add 4 inches → band size 34.
They also use double cups (DD, FF, GG) that do not exist in the EU scale.

United States
Similar to the British system with inches + cup letters, but cup sizes may differ slightly.
Example: US 34D ≈ EU 75D, US 36DDD ≈ EU 80E/F.
A US DDD ≈ UK E ≈ EU F, but this can vary between brands.

Italy
Has its own band size system with sizes 1–12 corresponding to EU band sizes + cup letter.
Example: Italian 2B ≈ EU 65B
Italian 3C ≈ EU 70C
Italian 4D ≈ EU 75D
Italian cup letters match EU in terms of cup volume, which makes both band and cup conversion relatively simple: the number converts and the letter corresponds to the same cup as in EU.

Japan
Band size in centimeters + cup letter.
Example: JP 75E ≈ EU 75D.
Japanese cups are often one step larger in letter than EU, meaning JP E corresponds to EU D.

Australia
Uses band sizes ranging from 6–30 + cup letters.
Example: AUS 10C ≈ EU 70C
AUS 12D ≈ EU 75D
AUS 14DD ≈ EU 80E
Band sizes follow roughly the same conversion as the UK (10 → EU 70, 12 → EU 75, 14 → EU 80), and the cups are close to the UK system, meaning DD corresponds to EU E.

Cup size is not universal

Even if the letters look the same (A, B, C, D etc.), they are not always the same size. A D‑cup in one country or brand may hold more – or less – than a D‑cup in another. Therefore, two bras with the same size label can fit differently on the body.

Think of it like this:
See bra sizing as a guide.

When you shop from a country that uses a different sizing system than what you are used to or try a new brand:

• Measure carefully and base your choice on your body measurements.

• Use size charts and guides.

• Focus on how the bra fits.

A bra that truly fits is ultimately most about fit and how it feels to wear, and least about what the size label says.