Essential Oils: The Size of One Drop

When using essential oils, we tend to talk in terms of using a certain number of drops. And so, you might wonder how many drops of essential oil are found in a five mL, 10 mL or 15 mL bottle.

And therein lies some confusion. I like to call this The Question of the Drop.

So let’s look at it from a scientific perspective and see if we can achieve some accuracy.

We’ll make one thing clear up front – all drops are not created equal. So armed with that knowledge, let us begin.

What is a Drop?

Another name for a drop is a minim.

And when I first studied this over 40 years ago, there were 15 minims to one mL, defining a minim {drop} as 1/15th of a mL and it related to pure water with the specific gravity of one. Instruments that dispensed drops {minims} were calibrated to this size. {And instruments that help count minims of the musical variety are called metronomes, but that’s a whole other story.}

Unfortunately, we human creatures seem to enjoy complicating things. Over the years, units of measurement have changed and even measuring systems between different global societies are not consistent. For example, a gallon of liquid in the UK or Australia is a different quantity from a gallon of liquid in the USA.

With the adoption of the metric system in many countries, some degree of uniformity has been achieved and now five mL should be the same amount whether it comes from Europe, Australia, China or the USA.  That said, it is a measure of volume dependent on temperature. So for accuracy, it should be stated as a certain volume at a specific temperature.

Now let’s come back to the practicalities of the drop. {I can wait while you inhale some Brain Power™ or Clarity™ essential oil blend if needs be. Hang in there …}

The size of the minim is different and it depends on where you are. For example, if you are in the UK, you’ll find officially 16.893638269379455 minims {drops} in one mL. If you are in the USA, there are 16.2307308763 minims {drops} per mL. However, this has nothing to do with the volume {millilitres in the bottle}.

It has to do with the size of the drop. Because there are a couple of other variables that come into play when talking about essential oils instead of pure water.

Every essential oil has a different molecular weight – some are thicker than others – and therefore specific gravity. So there can be no consistency between the number of drops of say lavender oil in a five mL bottle and the number of drops of vetiver in a five mL bottle when they are dripped through orifices that are roughly the same size. I say roughly because the dripolator in the bottle is commercially made and not calibrated scientifically, so there are small variances.

For practical purposes, should the levels of oil in a five mL bottle of lavender and five mL bottle of vetiver be the same?

Yes, allowing for manufacturing variables in the interior shape and size of the bottle.

But will there be the same number of drops?

Definitely not, because the drops are a different size.

Keeping all this in mind, I find this to be a fairly accurate yet conservative rule of thumb for the number of drops you will get out of a bottle, depending on the viscosity of the oil and the temperature of the environment:

5   mL =    75 drops

10 mL = 150 drops

15 mL = 225 drops

So, there you have it.  My answer to The Question of the Drop, based on my own experience {and some science to boot}.

PS:  The number of drops you will get out of a bottle is not the same as the number of drops that were put in. No matter how hard you try, there is always some oil left in the bottle. Perhaps the reason for this is the subject for another day?

Enjoy the good oil daily.

The information on this site does not constitute advice. Please consult with your health practitioner. When using any of the products mentioned throughout this site, please be sure to read the labels and follow their suggestions for safe use. Image © Young Living Essential Oils | Used with permission