Sister sizes are groups of bra-size equivalents that are related by cup volume. For example, a 36F (DDD) cup belongs to the same family as a 38E(DD), a 40D, and a 42C. Stick with us — we’ll explain. But just know that your perfect fit may still be out there waiting for you. And we’re going to help you discover yours.
(1) Do sister sizes really work?
Do you come across the situation that the bra you would like to buy runs out of your size? Do you feel that your current bra does not fit (band and/or cups) and need a better fit? If so, you need to know bra sister sizes, which can be a tremendous help for your bra fitting.
(2) How to use bra sister sizes?
Find your current bra size, and your sister sizes are the ones listed in the same row (going across). So, for example, if you’re a 34C, your sister sizes are 30E, 32D, 36B, and 38A. Each row is a family of sister sizes.
(3) Bra sister sizes chart
Below is a sister size chart from which you can find bra sizes that are related to your actual size. You should start with the size for which you have been measured, and the size that you are looking for in the lingerie shop. Moving along the same row, you will find the sister sizes that have the same cup volume.
Now you know the sister sizes, and hopefully this information helps alleviate some frustration for your bra shopping. Although the sister sizing is claimed to be accurate, it is possible to find exceptions, and for good reason. Women’s bodies are not the same, so sister sizing may not always work. The best option to get the best fitting bra is to get fitted and try on the various types of bras that catch your fancy.
PART 2: HOW TO MEASURE BRA SIZE?
1. How Do Bra Size Work?
Bra sizes are based on your band size (the number) and your cup size (the letter). These measurements are usually determined by using a tape measure around your rib cage and bust. The number/letter is your bra size. Finding the right bra size is crucial for the right support and for a smooth comfortable fit. To all the girls and women who have worn an ill-fitting bra or wrong bra size know that this can ruin a great outfit and even worse the entire day with backaches and pain.
(1) What does the number on a bra size mean?
The number or the 'band size' is a representation of your rib cage girth. We get this size by taking a measurement around your rib cage, about where the bra band sits. This measurement is taken in inches. As mentioned, this number gives us a guide to what size bra we need to accommodate the circumference of your rib cage, overlying skin and subcutaneous tissue.
(2) What does the letter on a bra size mean?
The letter component is an indication of cup volume. The amount of actual breast tissue/fat in volume.
(3) How 'the Number' and 'the Letter' work together on a bra size?
Understanding this is where the magic will happen for you when out bra shopping solo. Have you heard of sister sizing? That's what all of this is about... The band size will dictate how much cup volume your 'cup size' has.
2. Step-by-Step Guide to Measure Your Bra Size
(1) How to measure bra size with measuring tape?
Lots of us are wearing the wrong size, which means we don't look or feel as good as we should! Follow below to make sure you've got both your band and cup sizes just right.
STEP 1: Measure yourself
Wear nothing or a lightly lined (non-push-up) bra so your breasts are as close to natural as possible.
① Stand up straight and wrap the tape measure around your chest, just beneath the breasts. This is your BAND SIZE. Example: 38" ② Bend 45° use the tape to measure around the fullest part of your breasts. This is your BUST SIZE. Example: 41"
STEP 2: Verify your bra size
① Subtract the band size from the bust size. Example: 41"-38"=3" ② Find the final number below to get your CUP SIZE. Example: 3" = D cup
Band Size - Bust Size = Cup Size
③ Your BRA SIZE is your band size plus your cup size. Example: 38D
(2) How to measure bra size without measuring tape?
An accurate way to measure your bra size is with a measuring tape, that doesn’t mean you can’t figure out your correct bra size without one! It’s actually pretty easy to measure your correct bra size without a measuring tape, as long as you have an existing bra for reference.
You can use our Sizing Guide tool to help you learn your bra size without a tape measure so you can find the perfect bra fit straight away, or you can follow this guide to work your bra size out yourself.
STEP 1: Enter the size of the bra you’re currently wearing
Once you’ve opened any products, click ‘Sizing Guide’ and on the page choose your current band and cup size.
STEP 2: How does the bra band feel?
The band is the section that wraps around your torso under your boobs and around your back. Is your bra band too loose, too tight or just right ?
STEP 3: How does the bra cup feel?
If the cup gapes it is too loose, and if it creates over spill, it is too tight. The ideal cup will match the curve of the breast perfectly.
STEP 4: Discover your perfect bra size without a measuring tape!
If your band fits perfectly but the cup is too big or too small, you simply need to move up or down a size. For example, a 32B would move to a 32A if the cup is too big or a 32C if the cup is too small.
If your band is too big or small but the cup is just right, you need to move up or down a band size and move your cup size to your sister size. A sister size is the equivalent cup size on a different band length. When you move up a band size, you move down a cup size, and if you move down a band size you move up a cup size (provided the same cup size is needed). For example, a 32B is equivalent in terms of cup size to a 34A or a 30C.
Congrats, you’ve found the perfect bra size!
Now you know your correct bra size, it’s time to go bra shopping!
3. How Should Bras Fit?
How can I tell if my bra fits properly? Let’s check each part of the bra. When trying on your next bra, focus on the straps, the cups, the band, the underwire and the gore for the ultimate in comfort and support.
Straps: The straps are tightened so that they fit snug and comfortably on your shoulders. They shouldn’t slip off or dig into your shoulders. The straps should also be positioned in the center of each of your shoulders — not too far on the edge where it can slip off and not too close to the neck where it can feel uncomfortable. Cups: The cups should lay flush against your breast tissue without causing them to flow out of or gape within the cups. Band: The band should feel snug and comfortable on the loosest set of hooks. This allows you to move to the inner hooks to tighten the bra as it stretches with regular wear. Gore: Also known as the bridge of the bra which connects the two cups, the gore should lay flush against your sternum. It shouldn’t hover over the chest or dig in. Underwire: The underwire should lay comfortably under the breast tissue, providing support and without digging into the sides of the breast tissue or into the underarm area. The underwire shouldn't lay on your breast tissue or below your rib cage.
PART 3: BRA SIZE CALCULATOR
You can use our Sizing Guide tool to help you learn your bra size without a tape measure so you can find the perfect bra fit straight away, or you can follow this guide to work your bra size out yourself. Once you’ve opened any products, click ‘Sizing Guide’ and on the page choose your current band and cup size.
PART 4: FAQs ABOUT BRA SIZES MEASUREMENT
1. What is The Biggest Bra Size?
Technically, there is no limit to how big a bra size could be. There are over 250 bra sizes to choose from. Presently, the largest bra size ever recorded is 102ZZZ, belonging to Annie Hawkins-Turner (Norma Stitz), a woman from Atlanta, Georgia. She holds the Guinness World Record for the largest natural breasts. As you might have guessed, Hawkins-Turner has her bras specially made, as no store would carry her size.
Commercial bra cup sizes generally range from AA—the smallest—to M, N, or O—the largest—depending on where you are in the world and which brands are available. The most common range is A to DD, though there are specialty retailers where you can get your breasts sized by a professional then guided to a more expansive range of sizes—up to HH. Go shopping online and you might find plus size bras all the way to O size.
What’s the biggest cup size for bras? Interestingly, cup sizes vary from not just manufacturer and manufacturer, but also by country. Larger cup sizes often see the most variation. The smallest bra cup size is always going to be AA or AAA. The largest cup is often M in the US and N or O in the UK. Some countries, like Poland, have bra cups that go all the way to R.
2. What is The Smallest Bra Size?
Many people think that AA is the smallest bra size, but there is one that’s smaller: AAA. Since AAA is uncommon, you won’t see it in stores all that often, though specialty suppliers may carry it. The band and bust difference between A cups is slight, about 1 inch.
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