Practitioner Zone
Herbalist Calculators
A set of practical herbalist calculators — children’s dosing rules, extract-ratio and dry-herb equivalents, tincture-making and alcohol dilution, infusion strength, dropper conversions, and capsule filling.
A collection of small, no-nonsense calculators for everyday herbal work — converting doses, building tinctures, and brewing to strength. Everything runs in your browser; nothing is sent anywhere. Pick a tool from the index, or scroll through.
Extract Ratio Equivalent
Liquid extracts are labelled as a herb-to-liquid ratio. A 1:5 tincture is 1 g of
dried herb in every 5 mL; a 2:1 concentrate packs 2 g into every 1 mL. So each mL
carries herb ÷ liquid grams of herb. Enter a volume and ratio to see the
dried-herb equivalent — and convert the same dose between ratios, concentrates included.
Assumes the usual weight-to-volume convention (1 g dried herb per ratio mL). Real extracts vary with menstruum and herb; use this as a planning estimate.
Tincture Making
For a maceration at ratio 1:R, the menstruum is herb weight × R
(e.g. 100 g at 1:5 needs 500 mL). Then split that menstruum into your high-proof spirit and water
to hit a target alcohol strength: spirit = menstruum × target% ÷ spirit%,
and the rest is water.
Assumes dried herb and ideal mixing (alcohol/water volume contraction is ignored — close enough for tincturing). Fresh herb carries its own water and shifts the final strength.
Alcohol Dilution
Blend two strengths to hit a target — Pearson’s square. Leave the weaker one at 0% to dilute a spirit with plain water, or set it to another spirit’s strength to blend two.
Dry Herb Equivalent
Convert a concentrated extract into the weight of dried herb it represents — handy for reproducing the doses used in research. Enter the amount of extract, then the concentration: the percentage the extract weighs relative to the original dried herb.
A 13% extract means the extraction yielded a weight 13% of the starting herb, so 2 g of it represents 2 ÷ 0.13 ≈ 15.4 g of dried herb. The result keeps your entered unit and shows the mg ⇔ g conversion so it can’t be misread by 1000×.
Infusion / Decoction Strength
How strong is your brew? Enter the dried herb and the water it steeped (infusion) or simmered (decoction) in. A standard medicinal strength is around 1:20. One cup is taken as 240 mL.
Drops ↔ mL ↔ tsp
Translate a dose between drops, millilitres, and spoons. Droppers vary — the usual rule is about 20 drops per mL for a water-thin tincture, but thicker glycerites run fewer; adjust if you’ve counted your own.
1 tsp = 5 mL · 1 tbsp = 15 mL.
Capsule Filling
How many capsules a dose takes depends on the capsule size and how densely the powder packs. Pick a size for a typical fill weight, then fine-tune the milligrams if you’ve weighed your own — herb powders vary a lot in density.
Typical powdered-herb fills: 000 ≈ 1000 mg · 00 ≈ 600 mg · 0 ≈ 450 mg · 1 ≈ 300 mg · 2 ≈ 250 mg · 3 ≈ 200 mg. Approximate — weigh a few to calibrate.
Children’s Dosing
Six traditional rules estimate a child’s dose as a fraction of the adult dose, from age or body weight. Enter the child’s age first, then weight and the adult dose — every rule fills in at once so you can compare. The rule(s) appropriate for the age and weight you entered are highlighted green; faded cards mean the value falls outside that rule’s intended range. The rules don’t all agree — treat the spread as a sanity-check, not a single answer.
Fried’s Rule
Young’s Rule
Clark’s Rule
Augsberger’s Rule
Salisbury’s Rule
Cowling’s Rule
green = suited to this age/weight · faded = entered value is outside the rule’s range · the rest are general-purpose rules shown for comparison.
The formulas, for reference
Augsberger’s (birth onwards, by weight): (1.5 × weight in kg) + 10 = % of adult dose
Clark’s (~2–12 yrs, by weight): (weight in kg × adult dose) ÷ 67 = child’s dose
Cowling’s (by age): (age at next birthday ÷ 24) = fraction of adult dose
Fried’s (infants up to ~2 yrs): (age in months × adult dose) ÷ 150 = child’s dose
Salisbury’s (≤30 kg): (weight in kg × 2) = % of adult dose · (>30 kg): (weight in kg + 30) = % of adult dose
Young’s (~2–12 yrs): (age in years × adult dose) ÷ (age + 12) = child’s dose
Young’s is for older children, not infants — that range belongs to Fried’s.
Educational reference only — nothing here is medical or dosing advice. These are historical heuristics and planning tools, and can differ widely from each other and from modern guidance. Start low, account for individual sensitivity and interactions, and consult a qualified practitioner — especially when dosing children, during pregnancy or breastfeeding, or alongside medication. Many herbs are not appropriate for children at all.