How much essential oil goes in a batch of soap?
Start from the oil weight and a load: 1,000 g of oils at 2% is 20 g of essential oil in total — about 444 drops, which is why nobody counts drops for a full batch. That total is what you split across the blend. Two percent is the everyday load for essential oils in cold process (fragrance oils run higher, 3–6%); go to 3% for scents that fade in lye, like citrus, and stay nearer 1% for the strong ones — mint, clove, cinnamon leaf — and for anything with a low IFRA limit.
| Load | Per 1,000 g oils | ≈ Drops | Top (30%) | Middle (50%) | Base (20%) |
|---|---|---|---|---|---|
| 1% | 10.0 g | 222 | 3.0 g | 5.0 g | 2.0 g |
| 1.5% | 15.0 g | 333 | 4.5 g | 7.5 g | 3.0 g |
| 2% | 20.0 g | 444 | 6.0 g | 10.0 g | 4.0 g |
| 2.5% | 25.0 g | 556 | 7.5 g | 12.5 g | 5.0 g |
| 3% | 30.0 g | 667 | 9.0 g | 15.0 g | 6.0 g |
Drops at 20 per mL and 0.9 g/mL. Computed by this site's engine.
Top, middle and base notes — and the 30 / 50 / 20 rule
Perfumers sort scents by how fast they evaporate. Top notes (citrus, mint, eucalyptus, most herbs) are what you smell first and what fades first. Middle notes (lavender, geranium, rosemary, florals) are the body of the blend. Base notes (patchouli, cedarwood, vetiver, sandalwood, benzoin) are slow, heavy and long-lasting — and they anchor the faster oils so the blend doesn't vanish. A balanced starting point is about 30% top, 50% middle, 20% base by weight. In soap, which sits for weeks in an alkaline bar before anyone smells it, the base share is doing more work than it does in a perfume: push it up rather than down, and treat a top-heavy blend as something that will smell lovely in the mold and faint on the shelf.
20 g of essential oil at 30/50/20 is 6 g of top, 10 g of middle and 4 g of base notes. Put lavender in the middle slot, sweet orange on top and patchouli underneath, at 5 : 3 : 2 parts, and the tool prints those three weights and tells you the blend reads exactly 30/50/20. Add a second middle note and the “set parts” button shares the middle 50% between them.
Four starting blends, scaled to 20 g
| Blend | Oils (parts) | Grams each | Top / mid / base |
|---|---|---|---|
| Lavender garden | Lavender 5 · Rosemary 3 · Cedarwood 2 | 10.0 g · 6.0 g · 4.0 g | 30 / 50 / 20 |
| Citrus that lasts | Sweet orange (10-fold) 4 · Litsea (may chang) 2 · Patchouli 2 · Geranium 2 | 8.0 g · 4.0 g · 4.0 g · 4.0 g | 60 / 20 / 20 |
| Wake-up bar | Peppermint 3 · Eucalyptus 2 · Rosemary 3 · Vetiver 2 | 6.0 g · 4.0 g · 6.0 g · 4.0 g | 50 / 30 / 20 |
| Forest | Fir needle 3 · Cypress 3 · Cedarwood 3 · Vetiver 1 | 6.0 g · 6.0 g · 6.0 g · 2.0 g | 30 / 30 / 40 |
Starting points, not formulas — blend a few drops on a tissue first and smell it the next day. Check each oil's IFRA limit at your load.
A dropper gives about 20 drops per milliliter, and essential oils weigh about 0.9 g per milliliter, so a gram is roughly 22 drops — but thick oils like vetiver and patchouli drop slowly and large, thin citrus oils drop fast and small, and orifice reducers vary between suppliers by a third. Drops are fine for a 100 g test batch. Above a gram or two, weigh on a 0.01 g scale; the calculator shows drops only so you can check a tiny trial.
Which essential oils survive cold process?
Lavender, patchouli, cedarwood, vetiver, peppermint, rosemary, tea tree, eucalyptus, clove and cinnamon leaf all come through saponification and cure well. Cold-pressed citrus — sweet orange, lemon, lime, grapefruit — mostly does not: it is the classic “smelled amazing at trace, gone in four weeks”. Folded citrus (5× or 10×) holds far better, and so does anchoring citrus with litsea or a base note; that is what the “citrus that lasts” blend above is doing. Clove, cinnamon and some spice oils accelerate trace hard — keep them under 0.5% of oils and add at the last moment.