Talk:Drop (unit)

Fluid properties which influence drop size
I believe that drop size does not vary according to viscosity, but rather that it varies according to surface tension and density. Hence I have replaced "The size of drop may vary with the viscosity of the liquid" with "Drop size varies according to the density and the surface tension of the liquid." I have added the link to a reference that supports this, as well as a reference to the Webster Dictionary that relates to the preceding sentence. Dannybigd (talk) 13:07, 29 March 2010 (UTC)

Units systems
I removed: "This is similar to units like the cup, tablespoon, and teaspoon that depend on the spoon or cup." That sentence was following the paragraph that says ''"The volume of a drop is not well-defined: it depends on the device and technique used to produce the drop and on the physical properties of the fluid." ''

At least here in the US, a cup as a unit is 8 fluid ounces or half a US fluid pint. A Tablespoon is 0.5 fl. oz. and a teaspoon is a third of a Tablespoon. They seem to be set measurements to me and not something dependant on what ever cup or spoon is grabbed; rather a calibrated measuring device, though not 'laboratory grade' obviously, is used to measure these volumes. MetricUSA (talk) 02:32, 5 December 2007 (UTC)


 * Agreed. Here in Australia a cup is 250mL, conveniently close to the size of most coffee cups. There's something similar for teaspoons and tablespoons, since you can actually buy measuring spoons/cups with the measurement written on them. Not only that, the sentence jars with the preceding one, since the first talks about the physical properties that form a drop, while the second talks about units. LightYear (talk) 02:47, 10 December 2007 (UTC)

Drop in medical contexts
I'm a bit confused here. Medically, IV drops are counted as 10 per ml for regular IV sets, and 60 drops per ml for 'microdrip' sets. I don't see any reference to those in there, something I will add after I do some more cross checking. Also, listing 20 drops per ml for "metric drops" goes against common metric standards that require powers of ten. DocKrin (talk) 03:51, 11 March 2011 (UTC)
 * I've fixed the medical part. However, the 20 drops per mL is correct. Notice that "metric" is in quotation marks. The drop is obviously not part of the metric system. However, according to the scientists at Argonne National Laboratory, 50 microliters is the best estimate for the size of actual drops, in round numbers. Zyxwv99 (talk) 15:22, 8 March 2012 (UTC)

Accuracy: US fluid ounce
The math in this sentence must be incorrect:
 * The experiment shows that 5 drops of water equals 1 mL or about 150 drops equals 1-oz (US Fluid).

A U.S. fluid ounce is (approximately) 7.4 mL; therefore if a drop is 1/5 of that, there are 37 drops in a US fluid ounce, not 150. JustinTime55 (talk) 16:41, 10 December 2011 (UTC)

Webster's Dictionary
I changed this to Merriam-Webster, but...

Advice to College Writers: On Citing or Quoting your Trusty Webster’s, Encarta, or Wikipedia

Zyxwv99 (talk) 14:37, 19 December 2011 (UTC) Never mind, someone just took out the entire Webster definition, which is as it should be. Thanks. Zyxwv99 (talk) 16:29, 19 December 2011 (UTC)

5 drops one ml?
''5 drops of water equals 1 mL and about 150 drops equals 1-oz (US Fluid). A standard unit conversion gives (5.0 drops-water/1.0 mL-water) or (0.2 mL-water/1 drop-water).''
 * after that the text goes on to give different definitions of a drop, none of them close to this one. So where does it come from? 84.197.178.75 (talk) 21:20, 6 March 2012 (UTC)
 * Thanks for the heads up. I worked on this article a few months ago, then gave up because it was such a mess. I just finished cleaning up the rest of it. Not that anything is ever "finished", but at least it should be on the low end of acceptable. Zyxwv99 (talk) 15:24, 8 March 2012 (UTC)

metric drop really?
The reference for "metric drop" is a discussion forum post and does not use the term metric drop at all, only a "rule of thumb" of 1/20ml. If no one has a better source that should be removed or changed to reflect its "rule of thumb" status.

Anyone thinks its an actual unit should go ahead and add it to the SI units page ... — Preceding unsigned comment added by 132.3.33.68 (talk) 20:28, 20 July 2012 (UTC)


 * Thanks for the heads up. I've removed it. It was there before I arrived, although I made the mistake of providing a reference for it. Zyxwv99 (talk) 22:26, 20 July 2012 (UTC)

Subtle Vandalism?
I noticed that changed the volume in the History section from 0.05 ml to 0.041 ml. This is uncited, and while I don't have a reliable secondary source, nearly every unit converter I found agrees with the old value. I did find a few (mostly older) pharmacy references that indicated the drop is 1/15 (0.067) of a ml, but otherwise can't find anything supporting 0.041 ml, so this looks like it could be subtle vandalism.

The only changes after this were made to edit and amend this incorrect information, so I've reverted the article to the revision right before this. I'm happy to revert if someone can show a good source for 0.041 ml. Arathald (talk) 07:51, 22 March 2018 (UTC)