Soap Colorant Dosage Calculator
Calculate the right amount of colorant for cold or hot process soap.
Dosage for micas, oxides, clays, and botanicals.
How soap colorants work:
Soap colorants are added to the soap batter (usually at trace in cold process) to achieve the desired color. The amount needed depends on the type of colorant, the color intensity desired, and the total oil weight of the batch — not the total batch weight including lye water.
Dosage is always based on oil weight: Colorant % = (Colorant weight / Total oil weight) × 100
This is the industry standard because oil weight is the consistent base — water and lye amounts vary with recipes, but the oils are what carry the color.
Standard dosage rates by colorant type:
| Colorant Type | Light Shade | Medium Shade | Deep Shade | Max Safe |
|---|---|---|---|---|
| Micas (cosmetic grade) | 0.5 tsp/lb | 1 tsp/lb | 1.5 tsp/lb | 2 tsp/lb |
| Iron oxides | 0.25 tsp/lb | 0.5 tsp/lb | 1 tsp/lb | 1.5 tsp/lb |
| Titanium dioxide | 0.5 tsp/lb | 1 tsp/lb | 1.5 tsp/lb | 2 tsp/lb |
| Ultramarines | 0.25 tsp/lb | 0.5 tsp/lb | 1 tsp/lb | 1 tsp/lb |
| Activated charcoal | 0.5 tsp/lb | 1 tsp/lb | 1.5 tsp/lb | 2 tsp/lb |
| Clays (kaolin, bentonite) | 1 tsp/lb | 2 tsp/lb | 1 tbsp/lb | 1 tbsp/lb |
| Botanical powders | 1 tsp/lb | 2 tsp/lb | 1 tbsp/lb | 1 tbsp/lb |
Weight equivalents:
- 1 tsp mica ≈ 2.5 g
- 1 tsp oxide ≈ 3 g (denser)
- 1 tsp titanium dioxide ≈ 3.5 g
- 1 tsp charcoal ≈ 1.5 g (very light)
- 1 tsp clay ≈ 4 g
Worked example: A 900 g oil batch, medium purple using mica:
- Rate: 1 tsp per lb of oils
- Oil weight in lbs: 900 / 453.6 = 1.98 lb
- Micas needed: 1.98 × 1 = ~2 tsp = ~5 g
- For a swirl: divide into portions (e.g., 2/3 white titanium dioxide, 1/3 purple mica)
Color stability in soap: Not all colorants survive the high pH (9–10) of cold process soap:
- Stable: Micas, oxides, ultramarines, titanium dioxide, charcoal
- May morph: Lab-created FD&C dyes (some shift dramatically)
- Will fade: Most botanical powders (turmeric browns over time, spinach goes olive)
- Reliable botanicals: Indigo powder (blue), alkanet root (purple), annatto (orange), cocoa powder (brown), paprika (orange-peach)
Dispersion tip: Always pre-disperse powder colorants in a small amount of lightweight oil (1 tsp colorant in 1 tbsp oil) before adding to soap batter. This prevents clumping and streaking. For titanium dioxide, use a mini frother or stick blender to ensure smooth dispersion.
Multi-color and swirl techniques: Divide your soap batter at trace and color each portion separately. Use the same total colorant dosage — just split it across portions. For example, a two-color batch at medium shade uses 1 tsp/lb in each colored portion.