How to check an essential oil blend
To check an essential-oil blend, work out each oil's own concentration in the finished bottle and compare it against that oil's published maximum dermal level — then check the blend against the person and pets it will be around. Most free calculators only give you a single overall percentage, which is why a blend can look fine at 2% while one ingredient inside it sits ten times above its own limit. The analyzer above does both: it computes the per-oil percentages, checks them against the database, and grades the result out of 100.
What the analyzer checks
- Per-oil dermal limits. Each oil's concentration in your bottle against its own published maximum — the check that catches cinnamon bark, clove, oakmoss and lemongrass in otherwise ordinary-looking blends.
- Phototoxicity. Cold-pressed citrus oils have their own sunlight limits on leave-on skin products; the analyzer applies them only where they actually matter.
- Who it's for. Adult, child, infant, pregnancy and elderly ceilings, plus oils individually flagged unsuitable for those groups.
- Cats and dogs. Per-oil suitability for the animals in your home — a check no free web tool offers.
- Structure and evolution. Top/heart/base balance, the fragrance family your blend resolves to, projection and longevity, and a timeline of how it changes over the hours after application.
How the grade works
Each blend gets a score out of 100 — safety is worth half of it (50 points), then balance (25), structure (15) and character (10). The letter is always paired with a plain verdict, and the bands mean something specific: a dilution problem caps the total at 69, so a D or an F always means a published limit is exceeded — never just that the blend could smell better.
| Grade | Score | What it means |
|---|---|---|
| A — Well built, within limits | 90–100 | Every oil sits within its published dermal limit for this use, and the structure is balanced. |
| B — Good — one thing to note | 80–89 | No dilution problems. Either one oil isn’t suited to the person or pets you selected, or the structure could be tightened. |
| C — Workable, worth refining | 70–79 | Within its dilution limits, but the balance or structure is off — typically a missing note layer or one oil dominating. |
| D — Fix the dilution first | 60–69 | Something exceeds a published limit — an oil above its own dermal maximum, the blend above the ceiling for who it’s for, or a route that isn’t recommended. |
| F — Not safe as written | below 60 | More than one limit is exceeded. The blend needs changing before it goes on skin — the suggested fix is the place to start. |
Safe dilution at a glance
| Who it’s for | Body | Face | Bath |
|---|---|---|---|
| Adult | 3% | 1% | 2% |
| Child (2–6) | 2% | Not recommended | 1% |
| Infant (3–24 months) | 0.5% | Not recommended | Not recommended |
| Pregnancy | 1% | 0.5% | 1% |
| Elderly / sensitive skin | 1% | 0.5% | 1% |
Each oil's own limits are also listed on its page in the oil library.
Working the other way round?
If you know the strength you want and need the drop count, the Dilution Calculator converts any percentage into drops for roller bottles, sprays, diffusers, baths and more — sized to who it's for.
Open the dilution calculatorFrequently asked questions
How do I know if my essential oil blend is safe?
Check each oil individually, not just the total dilution. Every oil has its own published maximum dermal level — cinnamon bark is about 0.07%, clove around 0.5%, while many oils have no specific restriction. A blend can sit at a normal 2% overall and still hold one oil far above its own limit. The Blend Analyzer works out each oil’s concentration in your bottle and compares it against that oil’s published maximum, then layers on pregnancy, child, cat and dog suitability.
What does the A to F blend grade mean?
The letter summarises a score out of 100, and it is always shown with a plain-language verdict so you never have to guess. A (90–100) means every oil sits within its published dermal limit for that use and the structure is balanced. B (80–89) means no dilution problems, but one oil may not suit the person or pets you selected. C (70–79) is within limits yet unrefined — usually a missing note layer or one oil dominating. D (60–69) and F (below 60) always mean a limit is exceeded, because a dilution problem caps the score at 69. Safety is worth half the score, then balance, structure and character.
What dilution should an essential oil blend be?
For healthy adults, roughly 1% on the face, 2% for everyday body use, and up to 3% for short-term targeted use. Children, pregnancy, and older or sensitive skin need lower levels — around 0.5% for infants and about 1% in pregnancy. These are ceilings rather than targets, so starting lower is always reasonable.
Why does my blend smell good at first and then disappear?
Because it is probably all top notes. Volatile citrus and minty oils project hard for the first twenty minutes to an hour and then evaporate; without a heart and a base there is nothing left behind. A drop or two of a fixative base — cedarwood, vetiver, patchouli or frankincense — gives the blend a tail. The analyzer shows this as a timeline so you can see where your blend runs out.
Which essential oils are unsafe around cats?
Most of them. Cats metabolise many terpene compounds far more slowly than humans, so a large share of common oils are flagged unsuitable around them — including tea tree, eucalyptus, citrus oils, peppermint and pine. Tick “cat in the home” in the analyzer and it flags every oil in your blend that carries that caution. Diffuse only briefly in a ventilated room, always let the cat leave, and ask your vet.
Is the Blend Analyzer free, and do I need an account?
It is free and needs no account. Everything is computed in your browser from Dilutio’s oil database — no AI, no uploads. It is deliberately stateless: it does not save your blends. The Dilutio app is where formulas are stored, versioned and generated.
What is a top, heart and base note?
They describe how quickly an oil evaporates. Top notes are the most volatile and lead the opening (citrus, mint). Heart notes carry the middle and give a blend its body (lavender, geranium, rose). Base notes evaporate slowest, anchor the blend and extend its wear (vetiver, cedarwood, patchouli). A blend with all three usually reads as more complete than one built from a single layer.
The analyzer is a formulation aid, not a certification: it reports your blend against published dermal maxima and dataset safety flags, and it is for education only — not medical or veterinary advice. Always patch-test, and consult a qualified professional for use during pregnancy, on children, around pets, or with a health condition. Further reading: Tisserand Institute safety guidelines.