Here is how to dilute essential oils for hair: mix them into a carrier oil, such as jojoba or argan, at a low percentage before they touch your scalp. For a 1 oz (30 mL) bottle, a 1% dilution is about 6 drops of essential oil in total, assuming roughly 20 drops per mL. Gentle, at 0.5%, is about 3 drops. Patch test the blend before the first use, keep it away from your eyes, and choose only furocoumarin-free citrus oils for anything you leave on. In our blends, all essential oils together stay at or under 1% of the bottle.
Why essential oils need diluting
Essential oils are highly concentrated plant aromatics. Used neat, they are the most common cause of skin reactions to these oils. The Tisserand Institute's advice is short: do not apply undiluted essential oils to your skin.
There are two kinds of reaction to avoid. Irritation, such as redness, stinging or itching, fades once the oil is gone. Sensitization is an allergic response, and once you have it, it tends to return every time you use that oil, even at low strength. Dilution keeps the amount on any patch of skin small, which lowers the odds of either.
The carrier matters. Essential oils do not dissolve in water, so a few drops shaken into a water spray float on top and reach your scalp almost neat. Dilute in an oil. Our guide to carrier oils vs essential oils explains the difference between the two.
How much to dilute: rates for hair and scalp
Dilution is written as a percentage: the share of the finished blend that is essential oil, all of them added together. The Tisserand Institute's dilution guide gives ranges by use, including:
- 0.2–1% for skin that reacts easily
- 0.5–1.2% for the face and other sensitive areas
- 1–3% for body and massage oils
The scalp is skin, and a hair oil often stays on for hours. So we sit at the low end.
Our practice: 1%, or 0.5% for Gentle
In every hair blend we make, the essential oils together are at most 1% of the bottle at Standard strength and 0.5% at Gentle. Add a second, third or fourth oil and they share the same total; the total does not grow. Some oils have their own lower limits, which our builder enforces. Those limits are under review by a cosmetic chemist before launch, and we are not publishing them as general guidance.
If you are new to an oil, or your scalp is easily irritated, start at 0.5%. Go up only if you want more scent.
Essential oil dilution chart: drops per 30 mL (1 oz)
Drops are a convenient measure, not a precise one. The Tisserand Institute reviewed studies of drop size and found anywhere from about 20 to 40 drops per mL, depending on the oil and the dropper. The chart below works from about 20 drops per mL, and shows 30 per mL for comparison.
| Dilution | Essential oil in 30 mL | Drops at ~20 per mL | Drops at ~30 per mL |
|---|---|---|---|
| 0.5% (Gentle) | 0.15 mL | 3 | 4–5 |
| 1% (our maximum for hair) | 0.3 mL | 6 | 9 |
| 2% (body oils; above what we use for hair) | 0.6 mL | 12 | 18 |
The drop counts are totals for all essential oils combined. Three drops of lavender and three of rosemary in 30 mL is 1%, not 1% each. To scale up, multiply: a 4 oz (118 mL) bottle holds about four times as much.
If your dropper makes small drops, 6 drops will land under 1%, which is the safer side to err on. A wide dropper or a thick oil can push it over.
Why weighing is more precise
We do not count drops. We weigh every oil in a blend to the gram, and our percentages are by weight. A 30 mL bottle of carrier oil weighs roughly 27 g, so 1% is under 0.3 g of essential oil. At home you need a scale that reads to 0.01 g to work this way. If you have one, it is more reliable than any dropper.
How to dilute essential oils for hair, step by step
- Choose your carrier. Pick it for your hair: light oils such as jojoba for fine hair or the scalp, richer ones for thick or dry ends. Our guide to light vs heavy hair oils ranks them.
- Use a clean, dry amber or cobalt glass bottle. Light speeds up oxidation.
- Add the carrier first, leaving a little headroom.
- Add the essential oils using the chart above, counting the total across all of them.
- Cap and roll the bottle between your palms to mix.
- Label it with the oils, the dilution and the date.
- Patch test before the first full use.
How to patch test a new hair oil
A patch test will not catch everything, but it is the simplest check you can do. The American Academy of Dermatology recommends:
- Choose a quarter-sized spot where the product will not be rubbed or washed off, such as the inside of your arm or the bend of your elbow.
- Apply the amount you would normally use.
- Repeat twice a day for seven to ten days.
- If your skin turns red, itchy or swollen, wash the oil off gently and do not use it again.
No reaction after that time is a good sign. Test the finished blend, not the essential oil on its own: you never want neat oil on skin.
Safety notes: citrus oils, eyes and pregnancy
Phototoxic citrus oils, and why we use bergamot FCF
Some cold-pressed citrus oils, including bergamot, lemon, lime and grapefruit, are phototoxic: on skin exposed to sunlight they can cause burning or dark marks. Bergamot normally contains bergapten, a furocoumarin. The Tisserand Institute notes that once a phototoxic oil is on your skin, UVA exposure any time within the next 12 hours, possibly longer, can set off a reaction.
The fragrance industry's own standard, from IFRA, caps bergapten in leave-on products for sun-exposed skin at 15 parts per million. Our library avoids the problem by carrying only bergamot FCF. FCF stands for furocoumarin-free: the furocoumarins have been removed. If you blend at home with lemon, lime or grapefruit, choose a steam-distilled or FCF version for anything you leave on.
Eyes
Keep essential oils, and blends containing them, away from your eyes. Oil your scalp with your head tilted back, and wash your hands after. If any gets in your eyes, rinse well and get medical advice if discomfort continues.
Pregnancy, children and medical conditions
If you are pregnant or breastfeeding, talk to your doctor before using essential oils. Keep bottles out of reach of children. If you have a scalp condition or are noticing hair shedding, see a dermatologist rather than adjusting your oils.
Skip the counting
If you would rather not count drops, the five-question quiz suggests a full formula, scent optional. In the builder you choose up to four essential oils and a strength, Standard or Gentle, and the builder holds the total at 1% or 0.5%. We weigh each oil to the gram and print the formula on your label. For how to apply the finished oil, see how to oil your hair.
FAQ
How many drops of essential oil per ounce of carrier oil?
For hair, about 6 drops in total per 1 oz (30 mL) for a 1% dilution, or 3 drops for 0.5%, assuming about 20 drops per mL. Drop size varies, so read drop counts as approximate.
Is 2% too strong for the scalp?
It is a common figure for body oils, and above what we use. We keep hair blends at 1% or less, because a hair oil often stays on the scalp for hours.
Can I add essential oils to shampoo or conditioner instead?
You can, at the same low percentages. Products that rinse off leave less on the skin, but they still contact the scalp and can still irritate it, so the same care applies.
How long does a diluted blend keep?
That depends mostly on the carrier. Store it cool and out of light, and smell it before use: a sharp or stale smell means it has oxidized, and it is time to make a fresh one.
