Safety · Section 2 of 7
Dilution: the numbers and how to calculate
Recommended dilutions by person and by area of the body, and how to convert them into drops.
Dilution is not about making a bottle last longer. It is the condition for using an oil safely.
How to convert
One drop from a standard dropper is roughly 0.05 ml. The figure varies with the oil's viscosity and with the dropper, so treat it as an estimate rather than a constant.
From that: one percent in 30 ml of carrier oil is about 6 drops.
The formula: drops = carrier oil in ml × percentage × 0.2.
One thing that is easy to mix up if you make products to sell: the threshold for declaring on a label and the threshold for safe use are two different things. The list of allergens that must be labelled — covered on the regulations page — only answers the question of what you have to print on the box. It says nothing about what dilution is safe to apply, and a substance below the declaration threshold can still be too strong for someone's skin.
The first two rows for children carry no percentage, and that is deliberate. For children under two we give no figure at all — not for lack of space, but because this is where someone who sells raw materials has no authority. If you need to use something on a small child, ask a paediatrician rather than extrapolating down from the row below.
Recommended limits
| Situation | Dilution | In 30 ml |
|---|---|---|
| Adults, daily use over a large area | 1 % | 6 drops |
| Adults, short-term use on a small area | 2–3 % | 12–18 drops |
| Face | 0.5–1 % | 3–6 drops |
| Babies under 3 months | do not apply | — |
| Children 3 months to 2 years | do not apply; ask a paediatrician | — |
| Children 2 to 6 years | 0.25–0.5 % | 1–3 drops |
| Children 6 to 12 years | 1 % | 6 drops |
| Older people or sensitive skin | 0.5–1 % | 3–6 drops |
These are limits commonly given in the trade literature, not medical doses. They are cautious ceilings, and using less is always safer.
Patch test first
For every new oil, and for every new person:
Dilute to the strength you intend to use, put a small dot on the inside of the forearm, leave it and do not wash it off. Wait twenty-four hours. If there is redness, itching, burning or a rash, stop.
Sensitisation reactions sometimes appear late, so wait a full day rather than deciding after ten minutes.
Diffusing into the air
Three to five drops for an average-sized room, run in intervals rather than continuously — about thirty to sixty minutes, then a break.
The room must be ventilated. If there are small children, anyone with a respiratory condition, a pregnant woman or pets in the room, leave the door open and reduce the amount, or do not diffuse at all.
The nose adapts very quickly, so you will stop smelling the oil after fifteen minutes while the concentration keeps rising. Do not use your own impression as the measure.