sizecharts

Don't pick a brand or a size first.  Go by actual dimensions.

LENGTH is probably your most important measurement.  If you pick a cup that is too long, it will probably shift, leak and be uncomfortable.  If you pick a cup that is too short, you might have a hard time reaching it for removal.  Next period, reach in to feel how long your vagina is.
    If you can reach the end (not necessarily your cervix) easily, it's on the short side.
    If you have to reach really deep or still can't reach it, it's long.
    If it's in between, aim for a medium length cup.

WIDTH is measured at the rim.
    If you are young and/or new to inserting things into your vagina, you will probably want a narrow to medium width cup.
    If you are older and/or have had children, a medium to wide cup will probably suit you.

Once you have an idea of length and width preferences, use the size charts to eliminate the ones you don't think will fit.

The SHAPE of the cup probably has a greater influence than rim width on how "wide" a cup feels so also compare photos of those that fall into your fitment parameters.

It's not an exact science but getting into the right ball park will increase your chances of success greatly.


Being "tight" is a function of your pelvic floor (PC) muscles.  Cups sit above them. You need to relax them for insertion and removal and then you can go back to holding them as tightly as you normally do.  Above them, your vaginal wall muscles become less elastic as you age and/or have children.


There are more charts by other list members available at: http://menstrual-cups.livejournal.com/tag/faq

Melissa's side-by-side comparison photos:
http://menstrualcups.friendhood.net/f52-moderator-s-photo-library

Afriska's photos and guidelines:
http://en.afriska.ch/which-one-for-you1.html

The shading shows three different width ranges (narrow, medium, wide) and five different length ranges.
RED is discontinued, restricted distribution or otherwise hard to get
BLUE is "while supplies last" or not sold under that name any more

Keeper/MC - The Keeper and the US Moon Cup made by Keeper are identical in size and shape but are made of two different materials.

Si-Bell/Natu - Are apparently the same cup sold under different names.

NOTE: Just because there are clusters of many cups around a size range doesn't mean that they are most likely to fit the most number of people.  My personal pet peeve is that many cup manufacturers copy-cat each other but ignore the needs of others who beg for cups in other size ranges where the selection is poor or non-existent.  (Like long and narrow or super short and wide.)

Also: If you don't think a particular cup will fit you, don't buy it -- no matter how highly it is praised or recommended by others.