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Thank you for visiting. strives to increase both understanding and accuracy in the calculations of blending essential oils, or as they are sometimes called Recipes.

Our core feature is the The Essential Oil Dilution Calculator, located on the home page. We also have a second calculator, The MasterBlend Calculator, for use in calculating both the MasterBlend and the final dilution when used. There is also a page with detailed information on how the calculations are made, to what standard and whether it is important to have accurate calculations for your EO blends. 

We recommend starting with the "recipe" calculator on the home page. But, once comfortable with that, you should try out the MasterBlend calculator - handy for creating "bulk" blend bottles of your favorite blends. 

Again, thank you for stopping by. We hope this information is helpful to your Essential Oil journey

Table of Equivalents

The following is a brief outline of the table of equivalents used on

 drops ("20")

For a full discussion on this Table of Equivalents; their source; and details on what Drops ("20") are please see our explanation here.

Table of Equivalents

The following is the Table of Equivalents used on and in our calculations:

1.00000 ounce
6.00000 teaspoon
2.00000 tablespoon
0.12500 cup
29.57353 millileter
591.47060 drops (“20”)

The governing body in the United States for the standardization of weights and measures is the National Institute of Standards and Technology (NIST), U.S. Department of Commerce.  The current guidelines for Weights and Measures is published as NIST Handbook 44 – 2017, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, as adopted by the 101th National Conference on Weights and Measures 2016.

The Table of Equivalents used on are taken directly from Appendix C. General Tables of Units of Measurement, except for term “Drop”.  (Or, “Drop (“20”), as we list it.)

DROP (“20”) defined, as used on  1ml = 20 Drops (“20”)

Simply put, the (“20”) portion is always listed to remind you these calculations assume 1ml = 20 drops.

In the essential oil community, there is regular reference to the measurement(?) “DROPS”.  There is no legally standardized definition of this term in the official weights and measures of the NIST or other governing authorities.

Drops are typically measured as literal drops of liquid from eyedroppers, pippets, euro-droppers, etc.  There are various factors that affect the actual volume of liquid in a drop from a dropper. Orifice size of the dropper and the surface tension of the liquid are the two primary contributing factors.

The Effect of Differing Surface Tensions by Oil

To get an appreciation of the differences in surface tension, check out this page on Ananda Aromatherapy.

We will discuss variations in dropper orifice size below, but for this discussion, assume that the same dropper size was used for all these measurements.  They vary from 25-52 drops per milliliter, by various essential oils. Again, do not take these numbers for YOUR oil, as we do not know what size dropper orifice was used for their list, or used in your oils.

The Effect of Differing Dropper Orifice Sizes

Due to non-standardization of the term, the various droppers dispense a variety of drop sizes, even within the same defined word.  In Essential Oil Safety by Robert Tisserand, in Table 4.6 Calculating Essential Oil Concentrations, he states “these figures assume that 30 drops of essential oil = 1 mL”.  But, his footnote to the same table quotes from a 2001 Paper by K.P. Svoboda et al, An investigation into drop sizes of essential oils using different drop types, stating that “These figures are averages, as the number of drops per mL can vary from 20 to 40, according to the type of dropper.”

Getting specific information from the essential oil suppliers can be difficult, but in researching 18 suppliers websites, there were 8 with no direct information, 3 who like Tisserand used 30 drops = 1mL, and 6 that used 20 drops = 1mL. The 18th was the chart used above showing 25-52, by specific essential oil.  Additionally, most of the user groups and social media groups, as well as many bloggers, use the 20 drops = 1mL equivalency.

It is for this reason that highly recommends

  • Measuring only in the known equivalencies of Milliliter, Ounce, Teaspoon, Tablespoon and Cup
  • Using 0.05 mL instead of “Drop” (that would be 20 per milliliter)
  • Using measuring devices that allow for accurate measurements to go along with your accurate calculations

For more information on the impact of using drops and other errors made in calculations see Five Ways Your Dilution Ratios May Be Wrong.