Understanding P Size: Insight into Rare Bra Size

Written by Carmen Rodriguez

What Is a P Cup Size?

Understanding P Size Bras: Insight into Rare Bra Size. When it comes to bras, most people are familiar with cup sizes ranging from A to D or maybe DD. But breast sizes are highly diverse, and lingerie brands have responded by extending their size ranges. P cup bras fall into this extended sizing category, serving individuals with very full busts who need both specialized support and precise fit. Only select specialty retailers carry P cup sizes to accommodate those with larger busts.

While not commonly found in mainstream stores, P cup bras are vital for people whose bust volume exceeds more conventional cup sizes. This article explains the fit, structure, and support considerations required for P cup bras, and offers expert guidance for finding and wearing them confidently.

Understanding the Cup to Band Ratio

It’s important to understand that bra sizing is relative, a P cup doesn’t represent a fixed volume. Instead, the volume of a cup changes based on the band size. For example:

32P will have less cup volume than a 38P, even though the cup letter is the same.

This system is called “sister sizing.” The same cup volume can be represented by different cup letters depending on the band, as different bands can result in equal cup volumes due to the concept of sister sizing. In some sizing systems, certain band sizes are considered equal or equivalent to specific measurements in inches.

When determining your bra size, band measurement is the first step, measure just under the bust to find your band size. In the US, band sizes are always even numbers, so if your measurement falls on an odd number, round up to the nearest even number. Bust size is also a key factor in determining the correct bra size, as it influences cup volume and overall fit. That’s why accurate measurements and professional fittings are essential when navigating extended sizes like P.

How to Calculate Your Bra Size

Finding your correct bra size is the foundation for comfort, support, and confidence, especially when searching for less common sizes like P cup. Calculating your bra size involves two essential measurements: your band size and your cup size. Taking the time to measure accurately ensures your bra will fit snugly, provide the right support, and help you avoid common issues like discomfort or poor posture.

Step by Step Guide to Measuring

Band Size Measurement: Start by measuring your band size. Using a soft measuring tape, wrap it around your rib cage, just underneath your bust. Make sure the tape is level and fits snugly against your skin, but not so tight that it digs in. Note the measurement in inches. If you get an odd number, round up to the nearest even number, since bra band sizes are always even. This number is your band size.
Cup Size Measurement: Next, measure around the fullest part of your bust, keeping the tape measure level and comfortably snug. This is your bust measurement. Subtract your band size from your bust measurement, the difference in inches determines your cup size. For example, a 1-inch difference is an A cup, 2 inches is a B cup, 3 inches is a C cup, and so on.
Understanding Cup Volume: Remember, cup volume is relative to band size. For instance, a 34D and a 36D do not have the same cup volume; the 36D will be larger. This is known as “sister sizing,” where the same cup volume can be found under different band and cup size combinations.
Considering Breast Shape and Tissue: Every woman’s body is unique. Breast shape and tissue density can influence how a bra fits, so you may need to try different styles or sizes to find the best match. For example, women with denser breast tissue might need a different cup style for optimal support and comfort.

By following these steps and using a measuring tape, you can determine your band size, cup size, and start your search for bras that truly fit your body and lifestyle.

Understanding Your Results

Interpreting Measurements: Once you have your band and bust measurements, you can determine your bra size. For example, if your band size is 34 inches and your bust measurement is 37 inches, the 3-inch difference means you would wear a 34C. This method helps ensure your bra fits snugly around your rib cage and that the cups provide the right amount of coverage and support.
Finding the Correct Bra Size: The correct bra size should fit snugly but comfortably around your rib cage, with the band sitting level and secure. The cups should fully encapsulate your breasts without causing spillage, gapping, or discomfort. Adjustable straps should rest comfortably on your shoulders without digging in or slipping off.
European Bra Sizes and Other Considerations: Bra sizing systems can vary between countries. European bra sizes, for example, use different numbers and letters than those in the United States or United Kingdom. A US 32DD might be a European 70E. When shopping for bras internationally or online, always check the sizing chart to ensure you’re selecting the correct size for your measurements.
The Importance of Accurate Measurements: Wearing the correct bra size is about more than just comfort, it can help prevent skin irritation, back pain, and poor support, especially during physical activity. This is particularly important for women with larger cup sizes or certain medical conditions that require extra support.
Professional Fittings and Trying Different Styles: Many women find that professional bra fittings are invaluable, especially if you have a larger bust, unique breast shape, or have experienced changes due to pregnancy or weight fluctuations. Don’t hesitate to try different styles and sizes, as the right fit can vary between brands and bra designs.

By understanding your measurements and how they translate into bra sizes, you can confidently find bras that fit well, support your breasts, and enhance your comfort and style, whether you wear a DD, H cup, P cup, or any size in between. Accurate measurements lead to better support, improved posture, and the confidence you deserve every day.

Who Needs a P Cup Bra?

Individuals with a very large bust in proportion to their ribcage may require a P cup bra. Common challenges faced by those who wear this size include:

Finding sufficient support to prevent back, shoulder, and neck pain
Avoiding spillage, quad boob, or overflow from too small cups
Locating bras with strong materials that don't stretch out quickly
Achieving proper lift and shape without sacrificing comfort

People who have undergone hormonal changes, pregnancy, weight fluctuations, or genetic predispositions to larger breast tissue may find themselves in P cup territory.

Features to Look for in a P Size Bra

Bras in this size range must be engineered for maximum support and reinforced stability. Look for the following features:

1. Wide, Reinforced Straps

To evenly distribute weight and reduce shoulder strain.

2. Full Coverage Cups

Encapsulate the entire breast for comfort and containment.

3. Multi Part Cup Construction

Cut and sew cups (rather than molded ones) offer better structure.

4. Firm Under band Support

A snug, strong band is crucial, it provides 80–90% of the support in any bra.

5. Side Support Panels and Boning

Help control forward projection and underarm spillage.

6. High Center Gore

Stabilizes the bra at the front and helps separate the breasts.

Where to Shop for P Size Bras

Since P size bras are niche products, specialty retailers are usually the best source. Some trusted brands and boutiques include:

Elomi – Specializes in full bust and plus size lingerie. UK based brand offering an extensive range of cup sizes
Ewa Michalak – Polish brand known for precision in large-cup bras
Curvy Kate – Fun, fashion-forward bras for fuller busts
PrimaDonna – Offers luxury lingerie in extended sizes with superior craftsmanship

Availability of P cup bras may vary by country, and finding these sizes can be a challenge in many parts of the world.

Many online retailers also allow for virtual fittings and free returns, which is especially helpful for hard to find sizes.

Expert Tips for Wearing a P Cup Bra

Get fitted professionally at least once a year. Breast size can change with time.
Rotate between several bras to avoid wearing out the elastic too quickly.
Wash bras by hand or in a lingerie bag with mild detergent to preserve structure.
Don't settle for discomfort. A properly fitted P cup bra should lift, support, and shape without pain.
Consider specialty lingerie for activities like exercise, nursing, or sleep to maintain proper support in every context.

Final Thoughts: Support Without Compromise

Finding a P size bra can be challenging, but it's entirely possible and empowering, with the right knowledge and resources. No one should have to sacrifice comfort, style, or self confidence because of a limited size range. With expert construction and access to extended size specialists, you can find bras that fit beautifully, feel supportive, and enhance your everyday life.