Anyone who wears a bra needs to know which size she should be wearing. But most women don’t - we have all heard the depressing statistic that anywhere from 70%-90% of women are wearing the wrong size bra. I used to be one of those unfortunate women. When I had my first bra fitting, years overdue, I was completely blown away. I hadn’t even ever heard of my size and I actually started crying in the dressing room. I didn’t expect a bra size to have such an impact on me - after all, it’s just a number - but I also realized how completely far off someone can be from their correct bra size without even realizing how uncomfortable and unsupported she is. This is why I am so passionate about making sure all women know how to determine whether or not their bras fit them correctly. So, before you do any shopping with these gorgeous new collections coming out, be sure you know your correct bra size! I’ll give you some tips for sizing yourself, but please remember that there is no substitute for a quality bra fitting at a good, old-fashioned lingerie shop. This article is a lot longer than most that we post on The Lingerie Post, but it is an invaluable one that is long overdue!For a DIY fitting, there are three measurements you need to take. Put on your best-fitting bra before you take any measurements. It is best to have a friend help you take your measurements, but if you are careful you can manage it by yourself. This method will give you a general idea of your size for the majority of brands out there. Some counties use a different sizing system. If you use the metric system, just remember that one inch equals 2.54 centimeters. You can use this online calculator if you’re not sure.

First, you need to find your band number. Measure just under your bust, at the crease where your breast meets your ribcage. Measure all the way around your back, making sure the measuring tape is parallel to the floor. Make sure you are holding this snugly. Add five inches to this measurement. This is your band number. For example, if you measure a 33 inch ribcage circumference, your band size is approximately 38.

Second, confirm this measurement by measuring under your arms, across your back, and around the top of your chest. This number should be equal to the band size you calculated in the beginning (in this example, 38 inches).

Third, you need to determine your cup size. With your best-fitting bra still on, measure around the fullest part of your bust line. In this example, let’s say you took a bust measurement of 41 inches. To calculate your cup size, subtract the band measurement from the cup measurement. In this example, 41-38=3 inches. Every inch represents a cup size, so the final bra size would be a 38C.

1″ = A cup
2″= B
3″ = C
4″ = D
5″ or more = consult the links at the end of this article for information on larger cup sizing. It gets complicated!

If you are an odd number, you may try rounding down for better support. If that band size is a smidge too small, you can try buying a few bra extenders to use during the first couple months. If you round up, you will end up needing to replace your bras far more often as they wear out quicker.

This method only gives you an approximate idea of what your bra size is. Now, the fun part! Go shopping and try on a lot of bras. Don’t be afraid to make adjustments to your original calculation - everyone is different, and remember, it was just a good approximation. I actually wear a band one size smaller (and, consequently, one cup size larger) than my original calculations predicted, but if you know what to look for you can decide if adjustments need to be made.

Be sure to try on a new bra fastened on the loosest hook. As the bra wears out and the elastic begins to deteriorate, you will need to tighten it and move on to the other hooks. Your band needs to fit snugly - this is where the majority of your support is coming from! If your band rides up and is not perfectly parallel to the floor (even a bit lower in the back is good), like Rihanna’s bra in her latest video for “Hate That I Love You,” you are wearing a band size that is too big. Try going down a band size until it fits properly. Remember, when you go down a band size you must go up a cup size to maintain the same fit in your cups. If you find that the band on a 38C is too big, try on a 36D next. If your band on your 38C is too tight and painful, try a 40B.

If your breasts are not fully encased by the cup or the center gore does not lie flush against your breastbone, your cups are too small. The lovely Marissa Miller is wearing a cup size that is far too small, as you can see that the end of the underwires are touching breast tissue instead of lying flat against her sternum between her breasts. If you want cleavage like this, get a push-up bra in your correct size! If you have a “double-boob” effect as your breast tissue bulges out of your cups, you are wearing a too-small cup size. If your cups wrinkle or gap, you are wearing a cup size that is too big. Try going down a cup size.

Experiment! You may wear different sizes in different brands (just like jeans). If you are outside the range of normal department or lingerie stores, you’ll have to find a good lingerie shop or shop online. Watch our sale section for coupon codes offering free returns; this will be a lifesaver in the beginning!

Be sure to check out our bra sizing discussion in the forums!

For more information on bra sizing and other common issues, visit these sites for tips and help:

• Large cup conversion chart. It gets tricky after D cup! Larger-busted gals need to keep this chart handy.
• Great illustrated guide from Figleaves. Figleaves also has almost every bra size imaginable, in case you fall outside the “normal” size range.
• Victoria’s Secret knows their stuff, despite the fact that their catalog photos and sales associates don’t demonstrate that very well!
• The Boobologist can help diagnose common bra blunders after seeing a photo of you.
• Zafu gives instant bra suggestions after you answer a few questions about how your current bras fit.
• Intimacy can give you suggestions on bra size based on your shirt size, but it is not flawless. It’s a good place to start.