Breast size is mainly determined by your genes and weight. For example, if your mom has small breasts and you don’t have much body fat, you’re likely to have smaller breasts.

You may have heard that some products, such as special creams, or exercises will make your breasts bigger, but the truth is they don’t work. If you’re unhappy with the size of your breasts, you might find that some styles of tops or dresses are more flattering than others or you might try wearing a padded bra.

Every girl develops differently, so don’t be concerned if your breasts aren’t growing as fast as your friends’. They may continue to grow into your late teens or even early 20s.

Breasts can develop at different rates, so it’s perfectly normal for one to be bigger than the other. These differences tend to even out, but many fully developed women have breasts of different sizes, so it’s nothing to be concerned about if they don’t. If it makes you self-conscious, you can wear a padded bra or a bra with a pad on one side.

Genes and hormones control breast growth, so the fit of your bra won’t affect that at all. Your bra should be comfortable and provide enough support that your breasts don’t move or bounce too much.

In addition to keeping your breasts from bouncing around and improving their shape and appearance, a well-fitting bra can be helpful in other ways, including preventing injuries to breast tissue and improving your posture. Bras that don’t fit properly can cause back problems, muscle tension, and headaches.

The most accurate way to determine your chest measurement for your bra size is to run a tape measure just under your breasts, around your ribcage and back. The tape measure should lie flat and not be too tight or too loose. Note the measurement and add 5 inches to get your chest size. If you get an odd number, round down to the next number, not up, because bras tend to stretch.

To find out your cup size, run a measuring tape across the fullest part of your breasts, make a note of the number, and subtract your chest measurement from it. If the difference is less than 1 inch, your cup size is AA; if it’s 1 inch, you’re an A; if it’s 2 inches, you’re a B; if it’s 3 inches, you’re a C; and so on.

Sports bras, which are designed to prevent a woman’s breasts from moving around too much when she’s playing sports, can be good first bras for many girls because they have flatter cup areas. Some tops and dresses also have built-in bras, so you might not need a traditional bra for a while.

Because of genetics and hormones, some girls have more hair on their bodies than others, and this can include the area around the nipples. If you want to get rid of this hair, you can try tweezing or waxing, or talk with your doctor about other options, such as electrolysis or laser treatment (though those can be expensive).

It’s common to feel some pain or soreness in your breasts, particularly when they’re beginning to develop or during your period. Breast soreness is often part of premenstrual syndrome (PMS). Caused by changes in hormone levels, PMS also can include cramps, headaches, and mood swings. The soreness and the other effects of PMS should go away as your period starts. But breast swelling and tenderness can happen for other reasons, including pregnancy. It's important to know what is normal for you and to talk to a parent or your doctor if you are experiencing anything unusual.

A breast self-examination (when you examine your breasts for development and changes) can help women find cysts or other noncancerous breast problems between medical check-ups; it also may help detect breast cancer. Although breast cancer is extremely rare among teens, getting into the habit of checking your breasts can help you understand how they normally look and feel so it will be easier to notice anything unusual later on. Your doctor can show you how.