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Name: Julie L.
Status: student
Age: 20s
Location: N/A
Country: N/A
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.

Alcir Grohmann

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 well.

Vince Calder


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.

ProfHoff 354

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.
Assistant Director
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!


Dear Julie:

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.

Tom Douglas

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