Hair colour mixing
calculator.
Turn a formula in parts into exact grams, add developer at your brand's ratio, and blend two developers to the strength you need. Free, and nothing you type leaves your device.
1 · Formula mix — grams per shade + developer
Enter each shade in parts (e.g. 2 parts 7N + 1 part 7NA), the total colour you want in the bowl, and the colour-to-developer ratio from your brand's instructions.
2 · Developer blend — reach an in-between strength
Need a strength you don't stock, like 4.5% (15 vol)? Blend two developers from the same line. Mixing is by weight.
The target must be between the two strengths you chose.
3 · Developer strength chart — volume ↔ percentage, and typical use
| Volume | Peroxide | Typical use (rule of thumb) |
|---|---|---|
| 6 vol | 1.9% | Gloss, toning, demi-permanent deposit |
| 10 vol | 3% | Deposit only, or up to 1 level of lift |
| 20 vol | 6% | 1–2 levels of lift; standard grey coverage |
| 30 vol | 9% | 2–3 levels of lift |
| 40 vol | 12% | 3–4 levels with high-lift colour |
Rule of thumb only — lift depends on the colour line, the hair and processing time. Always check your brand's technical guide.
The maths
behind the bowl.
Shades from parts. Each shade's grams = total colour × its parts ÷ all parts. A 60 g bowl of 2 parts 7N to 1 part 7NA is 40 g and 20 g.
Developer from the ratio. Developer = total colour × the developer side of the ratio. At 1:1.5, 60 g of colour takes 90 g of developer — 150 g in the bowl.
Blending developers. To hit a strength between two developers, the stronger one's share is (target − weaker) ÷ (stronger − weaker). For 4.5% from 3% and 6%, that's (4.5 − 3) ÷ (6 − 3) = half of each.
Mixing questions,
answered.
What does a 1:1.5 mixing ratio mean?
One part colour to one and a half parts developer. With 60 g of colour you add 90 g of developer, for a 150 g bowl. The ratio comes from your colour line's instructions — common ones are 1:1, 1:1.5 and 1:2.
How do I split a formula like 2 parts 7N and 1 part 7NA?
Add up the parts (2 + 1 = 3), divide the total colour by that number, and multiply by each shade's parts. For a 60 g bowl that's 40 g of 7N and 20 g of 7NA. The calculator does this for any number of shades.
How do developer volumes convert to percentages?
10 vol is 3%, 20 vol is 6%, 30 vol is 9% and 40 vol is 12% hydrogen peroxide. Roughly, 1% equals 3.33 vol — so 1.9% is about 6 vol and 4.5% is 15 vol.
Can I mix two developers to get 4.5% (15 vol)?
Yes, if both are from the same brand and line. Equal amounts of 3% and 6% give 4.5%. For other targets, the share of the stronger developer is (target − weaker) ÷ (stronger − weaker). Always follow the manufacturer's guidance.
Which developer should I use to lift two levels?
As a rule of thumb, 6% (20 vol) lifts about 1–2 levels and 9% (30 vol) about 2–3. How much lift you actually get depends on the colour line, the hair and the processing time, so check your brand's technical guide.
Should I measure in grams or millilitres?
Use whatever unit your colour line specifies, and use the same unit for colour and developer — the ratio works the same either way. Weighing in grams on a salon scale is the most consistent.
Never work out a formula twice.
HueSuite saves every client's formula — shades, grams, developer, photos — and deducts the exact grams from your stock. 7 days free, no card.