There are a few things to consider before choosing the size of your cup. If you are young, a virgin, or just have a small vaginal canal, you’ll probably want to go with a teen size. If you’re sexually active or have given birth through C-section or have a heavy flow, you might be more comfortable with a Medium size. If you’ve given birth naturally and have a very heavy flow, you should go with a Large size. Ultimately, sometimes a trial-and-error system is what works best. At Cambio, we have a 60-day satisfaction guarantee, and if your cup doesn’t fit, we will exchange it for a new size for free.