Drops in ml
Name: Julie L.
Date: 2001 - 2002
I need to know how many DROPS of fluid are in one milliliter, and one
ounce. I have been totally unable to find this information
elsewhere. Thank you!
Hi, Julie !!!
In a general way, you may consider 0.04 ml / drop.
Of course, it depends on a number of factors like
type of solution, temperature, viscosity, etc.
The chemical "rule of thumb" for low viscosity liquids, the most common
type we encounter, like water and the common solvents, is 20 drops per ml
from a standard eye dropper or pipette. The "rule of thumb" works amazingly
The actual count will depend on the viscosity of the liquid and the size
of the dropper end. In general, there about 20 drops to one mL if the
liquid is water and delivered from a burette or medicine dropper.
The reason you have not found this number anywhere is that not all drops are
the same volume. It is like asking how many people make up one ton. The
size of a liquid drop will depend on the density of the liquid, its surface
tension, the size, shape, and composition of the nozzle, the flow rate of
the liquid through the nozzle...
That said, one mL is about twenty drops of water from an eyedropper.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
It depends on the size of the drop doesn't it? But you can try this
yourself. Get a dropper and a graduated cylinder that can measure 1 ml.
Count how many drops it takes. There should be a conversion factor for
ounces to ml, but I do not know what it is!
Unfortunately, drop size is not a constant -- it depends both on the
liquid and the opening from which it is falling. So, here the
experimental method is best. Get some of the liquid in question, and
let it drip from the intended dropper into a container with one or more
accurate volume markings on it. This is tedious, but very effective. A
small measuring cup or a shot glass should do. One thing that CAN be
looked up is the conversion of U.S. ounces to milliliters: 1 ounce is
equal to 29.57 milliliters.
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Update: June 2012