Essential Oil Dilution Cheatsheet (IFRA-Aligned)
Quick-reference table for safely diluting essential oils in DIY skincare and aromatherapy. Pregnancy, child, and sensitive-skin limits included. Based on Tisserand & Young + IFRA 51st amendment.
The 1% rule
The safest default for leave-on facial skincare is 1% maximum total essential oil load (= roughly 30 drops per 100ml carrier, or 6 drops per 30ml roller-ball).
If you only remember one number from this cheatsheet, remember 1% for face.
General usage rates by product type
| Product type | Adult max | Sensitive / pregnancy | Child (6+) |
|---|---|---|---|
| Face creams & serums (leave-on) | 1% | 0.5% | Avoid most EOs |
| Body lotions (leave-on) | 2% | 1% | 0.5% |
| Massage oils | 3% | 1% | 0.5-1% |
| Bath products (rinse-off) | 5% | 2% | 1% |
| Shampoo & washes (rinse-off) | 3% | 1% | 1% |
| Spot treatments (small area) | 5-10% in carrier | Avoid | Avoid |
| Solid perfumes | 5-15% | Avoid | Avoid |
| Cleaning sprays | Up to 10% | n/a | n/a |
Per-EO dermal maximums (from Tisserand & Young + IFRA)
These are the hard ceilings — never exceed in leave-on cosmetics.
Restricted EOs (use under 1%)
| Essential oil | Max leave-on | Notes |
|---|---|---|
| Bergamot (whole) | 0.4% | Phototoxic — use FCF (bergaptene-free) instead for higher % |
| Cinnamon Bark | 0.07% | Severe sensitiser |
| Cassia | 0.05% | Even harsher than cinnamon |
| Clove Bud | 0.5% | Sensitiser |
| Lemon (cold-pressed) | 2% | Phototoxic |
| Lemongrass | 0.7% | Citral sensitiser |
| Lime (cold-pressed) | 0.7% | Phototoxic |
| Rose Otto | 0.6% | Methyleugenol limit |
| Tagetes | 0.01% | Phototoxic |
| Ylang Ylang (Complete) | 0.8% | Sensitiser |
Moderately restricted (1-3%)
| Essential oil | Max leave-on | Notes |
|---|---|---|
| Cedarwood Atlas | 1.5% | Pregnancy caution |
| Geranium Bourbon | 17% | Generous limit |
| Helichrysum italicum | 0.5-2.5% | Chemotype-dependent |
| Juniper Berry | 2% | Pregnancy caution |
| Lavender (true) | No limit | One of the safest |
| Myrrh | 2% | Pregnancy caution |
| Peppermint | 5.4% | Avoid in children under 6 |
| Rosemary CT Verbenone | 6.5% | Gentler chemotype |
| Sandalwood | No limit | Sustainability caution |
| Tea Tree | 15% | Watch oxidation |
Generally unlimited (still patch test)
Chamomile German, Chamomile Roman, Frankincense, Lavender True, Niaouli, Petitgrain, Spearmint (under 1.7%), Vetiver.
⚠️ Avoid entirely in pregnancy
Anise, basil, birch, camphor, cinnamon, clary sage (early pregnancy), clove, fennel, hyssop, jasmine, juniper, marjoram, mugwort, myrrh, nutmeg, oregano, parsley, peppermint (esp. 1st trimester), pennyroyal, rosemary (CT camphor/cineole), sage, savory, tansy, tarragon, thyme (CT thymol/carvacrol), wintergreen, wormwood.
⚠️ Avoid in children under 6
Camphor, cinnamon, clove, eucalyptus, peppermint, rosemary, wintergreen — all carry respiratory or hepatotoxicity concerns in young children.
⚠️ Toxic to cats
Tea tree, peppermint, eucalyptus, citrus, cinnamon, clove, pine, wintergreen, ylang ylang, lemon, lavender (in some studies) — avoid in any product applied near cats.
Phototoxic EOs (sun-exposed skin)
These cause severe phototoxic burns within 12-72h of application + sun exposure. Limit STRICTLY for leave-on, or use distilled / FCF (furanocoumarin-free) versions:
- Bergamot (whole) → use bergaptene-free version for safe use
- Lemon (cold-pressed) → use steam-distilled for safe use
- Lime (cold-pressed) → use steam-distilled for safe use
- Grapefruit (cold-pressed) → mild risk
- Bitter Orange (cold-pressed) → mild risk
- Tagetes → use under 0.01%
- Angelica Root → use under 0.8%
Conversion: drops to percent
For most EOs, 1ml ≈ 20 drops. So:
- 1% of 100g formula = 1g EO = ~20 drops
- 1% of 30g roller-ball = 0.3g EO = ~6 drops
- 0.5% of 30g roller = 3 drops
- 2% of 100ml body oil = 40 drops
For very thick EOs (vetiver, patchouli, sandalwood) 1ml ≈ 25-30 drops.
Storage rules
- Amber glass only — clear bottles + light = rapid oxidation
- Cool & dark — fridge ideal for citrus and other oxidation-prone EOs
- Small bottles — don’t buy 100ml of an EO you’ll use 10ml/year (oxidation accelerates as the bottle empties and air fills the headspace)
- Date the bottle on opening
- Replace annually for citrus, tea tree, conifer EOs (high oxidation rate)
- Most EOs last 2-3 years sealed and cool; patchouli, sandalwood, vetiver, frankincense improve with moderate aging (5+ years)
Always patch-test
Apply 1 drop of diluted EO blend (at intended use %) to the inside of the elbow. Wait 24-48h. If no reaction, proceed. New customers, new EOs, new chemotypes — patch test every time.
Sources: Tisserand & Young, Essential Oil Safety, 2nd ed. (2014); IFRA Standards, 51st amendment.
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