Developer Mixing Calculator

How it works

Permanent and demi-permanent hair color is mixed with a developer — a hydrogen peroxide cream — just before use. The developer to hair color ratio sets how much of each goes in the bowl, and the developer's volume sets how strong it is. The calculator handles both and checks your hair's history for risks.

1. The amount comes from your color's ratio

Developer amount = color amount × ratio. At 1:1, 60 g of color takes 60 g of developer; at 1:2 it takes 120 g. You can work in grams or ounces — just measure both parts the same way. We don't assume a brand's ratio because lines differ; read it from your instructions.

2. The volume comes from your goal

The calculator uses the general guidance most colorists learn: 10 volume (3% peroxide) to deposit or tone, 20 volume (6%) for gray coverage and about 1–2 levels of lift, 30 volume (9%) for about 2–3 levels, and 40 volume (12%) for about 3–4 levels. Where guidance overlaps — 2 levels can be 20 or 30 volume — it tells you so. Your color manufacturer's instructions always win.

3. The risk comes from your hair's history

Relaxers and lighteners both break bonds inside the hair, so stacking them raises the chance of breakage. Lightening relaxed or bleached hair is flagged as high or very high risk with a clear recommendation to see a licensed colorist. Previously colored hair gets a different warning: permanent color doesn't lift old color.

4. Safety steps that never change

Every result repeats the same checklist: a skin patch test 48 hours before every color, a strand test, gloves, the processing time on your instructions (typically 30–45 minutes) and no color on an irritated scalp.

Limits

• This is general guidance, not a formula for a specific product.
• It cannot predict allergies, the final shade or how your hair will react — that is what patch and strand tests are for.
• Burning, swelling or blistering during or after color needs medical attention right away.