Essential Oil Blend Calculator

It always computes a normalizer as 100 divided by your total percentage, so if your top, middle, and base note percentages already sum to exactly 100, the normalizer is simply 1 and nothing changes. The normalization only has a visible effect when your entries sum to something other than 100 — say 90 or 110 — in which case each note's share is scaled proportionally so the drop allocation still adds up correctly.

Each tier's drop count is rounded independently to a whole number, and those three roundings won't always sum back to your exact total drop count. The calculator detects that shortfall or surplus (roundingAdj) and adds or subtracts it from the top or base note specifically, so the three tiers always sum exactly to your requested total even though one note absorbs the rounding difference.

That figure is a widely used industry approximation for a standard essential-oil dropper, used only to give you a rough total volume so you can pick an appropriately sized bottle. Actual drop volume varies with an oil's viscosity and the specific orifice reducer on the bottle, so it isn't precise enough to rely on for measured dosing.

Top notes (citrus, mint, eucalyptus) are the most volatile and evaporate fastest, so they form your first impression of the scent but fade within minutes to an hour. Middle notes (lavender, rosemary, chamomile) evaporate more slowly and make up the perceived body of the blend, while base notes (cedarwood, vanilla, sandalwood, patchouli) evaporate slowest of all, lingering longest and anchoring the other two layers as they fade.