Natural Dye Calculator & WOF Chart
Enter the dry weight of your fabric or yarn and get exact grams of dye, mordant, tannin and water. Free to use, for wool, silk, cotton and linen. Charts and sources are below.
| Step | Ingredient | % WOF | Amount |
|---|
The 1-2-3 fructose vat: 1 part natural indigo, 2 parts slaked lime (calcium hydroxide), 3 parts fructose, by weight.
| Ingredient | Per litre | Amount |
|---|
Formula: grams needed = dry fiber weight in grams × % WOF ÷ 100.
Starting points only. Results vary with water, fiber and each natural batch: always test a small sample first.
What does WOF mean?
WOF means weight of fiber (also written WOG, weight of goods, or OWF, on weight of fiber). In natural dyeing every amount of dye, mordant and tannin is a percentage of the dry weight of the fiber you want to dye. Recipes written this way scale up and down easily, from a small test swatch to a full dye pot.
The formula: grams needed = dry fiber weight in grams × % WOF ÷ 100.
Example: you want to dye 250 g of cotton fabric with madder extract at 5% WOF. 250 × 5 ÷ 100 = 12.5 g of madder extract. For an alum mordant at 12% WOF you need 250 × 12 ÷ 100 = 30 g of alum.
Always weigh the fiber dry, before you wet it. A digital scale that reads to 0.1 g helps for extracts and iron, which are used in small amounts.
Natural dye WOF chart
Starting rates for the dyes we sell. "Light", "medium" and "deep" are typical ranges on well-mordanted fiber. Raw plant powders are used at much higher rates than concentrated extracts.
| Dye | Light | Medium | Deep | Colors |
|---|---|---|---|---|
| Madder root powder | 20–30% | 40–60% | 80–100% | Pink, coral, brick, true red |
| Madder extract | 2–3% | 4–6% | 8–10% | Pink to deep red |
| Weld powder | 20–30% | 40–60% | 80–100% | Lemon to golden yellow |
| Weld extract | 0.25–0.75% | 1–2% | 3% | Bright, clear yellow |
| Persian berry powder (buckthorn) | 5–10% | 10–20% | 25–30% | Warm golden yellow |
| Persian berries, whole (buckthorn) | 10–20% | 25–35% | 50–100% | Golden yellow (crush first) |
| Persian berry extract (buckthorn) | 2–4% | 5–6% | 8–10% | Golden yellow |
| Pomegranate peel powder | 10–15% | 20–30% | 40–100% | Yellow, khaki; olive and grey with iron |
| Black walnut hull powder | 10–25% | 30–50% | 75–100% | Beige to dark chocolate (no mordant needed) |
| Onion skins | 20–30% | 50% | 100% | Gold, orange, rust |
| Oak gall powder + iron | 8–10% | 15–20% | 20–30% | Silver grey to charcoal |
| Natural indigo | 2 / 4 / 8 g per litre of vat (see the indigo chart below) | Sky blue to navy | ||
Safflower works differently (separate yellow and red extractions), so it is not in the calculator. See the safflower recipe.
Mordant and tannin chart
| Ingredient | Wool & silk | Cotton & linen | Notes |
|---|---|---|---|
| Alum (potassium alum) | 10–15% (start at 12%) | 12–15%, after tannin | Wool: 80–85 °C (175–185 °F), 45–60 min. Silk: under 70 °C (160 °F). Cotton: hot water, then soak overnight. Over 20% can make wool sticky. |
| Cream of tartar | 5–7% (wool) | Not used | Keeps wool softer and colors brighter. |
| Soda ash with alum | Not used | 1.5–2% | Neutralizes the alum on plant fibers. Add slowly: it fizzes. |
| White oak gall powder | Optional | 8–15% (start at 10%) | Clearest tannin: keeps colors bright. |
| Green oak gall powder | Optional | 8–15% (start at 10%) | Strong tannin, pale cream tone. |
| Sumac leaf powder | Optional | 20–40% (start at 30%) | Soft yellow tone. |
| Pomegranate peel (as tannin) | Optional | 20–30% | Adds a yellow tone. |
| Acorn tannin extract | Optional | 5–10% (start at 8%) | Concentrated extract. |
| Red pine bark extract | Optional | 5–15% (start at 10%) | Warm pink-tan tone; good under reds and browns. |
Read more: alum mordant guide · mordanting wool and silk · mordanting cotton and linen · natural tannins compared.
Modifiers and assists chart
| Ingredient | Rate | Use |
|---|---|---|
| Iron (ferrous sulfate), afterbath | 0.25–1% on wool and silk; 0.5–2% on cotton and linen | Darkens and cools colors: olive, plum, grey, black. Warm water, 5–15 minutes, then rinse well. |
| Iron as a mordant | 2–4%, never more than 4% | Cotton and linen only. Too much iron weakens fibers. |
| Calcium carbonate (chalk) | 1–6% in a madder bath (start at 2–3%); 4–8% with weld powder; about 1% with extracts | Deeper, truer reds and stronger yellows, mainly in soft water. Not a mordant. |
| Soda ash, scouring | 2–5% for cotton and linen | Removes waxes and finishes before mordanting. |
| pH-neutral wool wash, scouring | 1–2% | Gentle scour for wool and silk. |
| Gum arabic | About 1 part gum to 4 parts liquid as a starting point; adjust to the thickness you need | Thickens mordant and dye pastes for printing and painting. |
Indigo vat chart (1-2-3 fructose vat)
Indigo is measured per litre of vat, not by WOF. The 1-2-3 vat uses 1 part natural indigo, 2 parts slaked lime (calcium hydroxide) and 3 parts fructose, by weight.
| Vat | Indigo | Slaked lime | Fructose | Result |
|---|---|---|---|---|
| Light | 2 g/L | 4 g/L | 6 g/L | Sky and pale blues |
| Medium | 4 g/L | 8 g/L | 12 g/L | Mid blues |
| Dark | 8 g/L | 16 g/L | 24 g/L | Deep blue to navy (with several dips) |
Keep the vat at about 30–50 °C (86–122 °F). Aim for pH 9–10 for wool and silk and 11–12 for cotton and linen. Full method: indigo vat guide.
How much water?
Use about 2–4 litres of water per 100 g of fiber (a liquor ratio of 1:20 to 1:40) for scouring, mordanting and dyeing. The fiber should move freely in the pot. Too little water is a common cause of patchy color. The amount of water does not change the amount of dye or mordant: those depend only on the fiber weight.
Tips for repeatable results
- Test first. Water, fiber and each natural batch differ. Dye a small swatch before a big piece.
- Keep notes. Write down fiber weight, % WOF, temperature and time. The calculator's "Copy recipe" button helps.
- Use separate pots for iron, and never use your dye pots for food.
- Judge color dry. Wet fiber looks darker.
- Wear a dust mask when measuring fine powders, and gloves for iron and walnut.
Where these numbers come from
We checked our rates against expert natural dye suppliers and teachers, peer-reviewed studies and our own test swatches. When sources disagree, we give the common middle range and a safe starting point. Key references:
- Assefi Pour & He (2020), madder and alum on wool, Coatings 10(1):78. Alum at 10% WOF gave stronger color than 20%.
- Bukhari et al. (2017), walnut (Juglans regia) dyeing and fastness, Textiles and Clothing Sustainability 3:3.
- Wilson, Carr & Hacke (2012), iron-tannate dyed textiles, Chemistry Central Journal 6:44. Iron with tannin speeds up fiber weakening, which is why we keep iron low.
- Inan, Kaya & Kirici (2014), effect of dye plant amounts on color of wool yarns, Industria Textila 65(1).
- Mohtashim, Farooq & Asim (2024), indigo dyeing of cotton with reducing sugars, Pigment & Resin Technology. Fructose gave the best reduction.
- Patwary & Haar (2016), sumac leaves as a natural mordant on cotton, ITAA Proceedings.
- Practitioner guides from Maiwa, Botanical Colors and Wild Colours.
Frequently asked questions
How do I calculate WOF for natural dyeing?
Weigh your fiber dry. Multiply the dry weight in grams by the percentage and divide by 100. For 200 g of wool and 12% alum: 200 × 12 ÷ 100 = 24 g of alum.
How much alum do I need per 100 g of fabric?
For wool and silk use 10–15 g of alum (10–15% WOF), starting at 12 g. For cotton and linen use 12–15 g of alum after a tannin bath, with 1.5–2 g of soda ash.
How much natural dye do I need?
It depends on the dye. Raw plant powders such as madder root or weld powder are used at about 25–100% WOF. Concentrated extracts are used at about 0.5–10% WOF. Use the chart above for each dye.
Does the amount of water change the recipe?
No. Dye and mordant amounts depend only on the dry fiber weight. Water only needs to cover the fiber so it can move freely, about 2–4 litres per 100 g.
Is the calculator accurate for every dye batch?
The numbers are tested starting points. Natural materials, water and fibers vary, so dye a small test swatch first and adjust.
Related: Mordants for natural dyeing · Natural dye color chart · Shop natural dyes and mordants