People are commonly confused when they read tincture directions suggesting they take a "dropperful" or two of a tincture. When they squeeze the bulb on the droppertop, they are surprised to see that it fills the glass tube only a little bit of the way. They try to squeeze harder to try to fill it completely, but it never works. This is why:
There are many, many different sizes of tincture bottles with droppertops (and glass tubes) that fit each size. Some are very tiny, and some are very large. The tiny bottles will have short glass tubes attached to the droppertop, and the large ones will have a very long glass tube. The squeeze bulb on them all, however, is all the same size. When you squeeze it, it will draw the same amount of liquid into the glass tube no matter how long or short it may be. This way, you get a standard dose each time. Otherwise, you would get only a little – an under-dosage - with the small, short one - or an over-dosage with a large one.
For more detailed information on tinctures, how to take them, what they are, please see this Article.