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Hair colour mixing & hair growth calculators

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Hair dye developer mixing calculator

Pick the developer strength and mixing ratio on your colour's instructions, then enter a tube size or the total you want. You get grams, millilitres or ounces for the bowl, plus what each strength is normally used for.

1Developer strength
vol
%

20 vol (6 %)

The everyday strength for permanent colour: covering grey and staying at the same level or going slightly lighter.

Lift: Up to about 1–2 levels.

2Mixing ratio (colour : developer)
3How much to mix

Mixing formula

Your bowl

Colour
60 mL≈ 2.05 fl oz
Developer
60 mL20 vol (6 %)
Ratio
1 : 1 colour : developer
Total mix
120 mL≈ 4.05 fl oz
50% colour

Measured by volume, for example with a measuring bottle or the scale on a developer bottle. Colour cream and developer weigh close to 1 g per mL, so weighing gives nearly the same result.

How to use it

  1. Developer strength. Tap 10, 20, 30 or 40 vol, or type either number: volume and percentage stay linked. The card below explains what that strength is normally for.
  2. Ratio. Choose the colour-to-developer ratio from your colour's instructions. 1 : 1 means equal amounts; 1 : 1.5 means one and a half times as much developer as colour; 1 : 2 means twice as much. Custom takes any ratio, such as 1 : 2.5.
  3. Amount. Start from the colour you have (a 60 mL tube, half a tube), from a total you want to end up with, from the developer left in a bottle, or let the estimate suggest a range for your hair length and thickness.

Worked example

A 60 mL tube of permanent cream mixed 1 : 1.5 needs 60 × 1.5 = 90 mL of developer, giving 150 mL in the bowl. Want 120 g in total at 1 : 2 instead? One part in three is colour: 40 g colour and 80 g developer.

Grams or millilitres? Professional colour is often weighed on scales. Colour cream and developer weigh roughly 1 g per mL, so either works as long as you use the same unit for both. Ounces here are weight ounces (28.35 g); fluid ounces are US (29.57 mL).

Developer strengths at a glance

“Volume” is how many volumes of oxygen gas one volume of the developer can release. The trade rounds 3 % hydrogen peroxide to 10 volumes, so each 1 % is about 3⅓ vol.

VolumePeroxideTypically used for
10 vol3 %Deposit only: toners, tone-on-tone, going darker
20 vol6 %Standard permanent colour and grey coverage; up to about 1–2 levels of lift
30 vol9 %More lift, up to about 2–3 levels
40 vol12 %High-lift blonde shades and lighteners made for it, up to about 3–5 levels; the EU maximum for hair products

Lift depends on the brand, the shade and your starting colour. L'Oréal Professionnel rates its cream developer at up to 2 levels at 20 vol, 3 at 30 vol and 4–4½ at 40 vol (with high-lift shades only). Wella mixes its standard Koleston Perfect shades 1 : 1 and its Special Blonde shades 1 : 2, with up to 3 levels of lift at 9 % and 5 at 12 %.

Sources

  • U.S. Food and Drug Administration, Hair Dyes: skin test before every use, the caution that dyeing eyelashes or eyebrows may cause blindness, gloves, rinsing and not leaving dye on longer than directed.
  • NHS, Hair dye reactions: testing at least 48 hours before use, PPD, black henna, symptoms and when to call 999.
  • DermNet, Allergy to paraphenylenediamine: where PPD is found and why reactions can get worse with repeated exposure.
  • Regulation (EC) No 1223/2009 on cosmetic products, Annex III: hydrogen peroxide in hair products up to 12 % (40 volumes) with the warning to avoid contact with eyes; the label warnings for oxidative hair dyes, including use by under-16s and black henna.
  • Health and Safety Executive, COSHH and hairdressers: gloves for colouring and bleaching, and ventilation because dusty bleach products can cause asthma.
  • L'Oréal Professionnel, Cream developer: 1 : 1.5 mixing with Majirel and lift by volume. Wella Professionals, High lift blonde hair color: 1 : 1 and 1 : 2 ratios and lift by strength.

The amount estimate is our own rule of thumb from typical salon practice, not a published standard. Your hair's density, porosity and the way the colour is applied all change how much you need.

More from the salon chair

Plan your growth, time each step and name your length.

Questions

What does 20 volume developer mean?

It is developer with about 6 % hydrogen peroxide: one volume of it can release about 20 volumes of oxygen gas. The trade uses round numbers, so 10 vol is 3 %, 20 vol is 6 %, 30 vol is 9 % and 40 vol is 12 %.

Can I use a stronger developer to make the colour work faster?

Use the strength your colour's instructions name. A stronger developer lifts your natural pigment more, which changes the result, and it is harder on hair and more likely to irritate the scalp. It does not shorten the processing time the product states.

What happens if I get the mixing ratio wrong?

Too little developer can leave colour that does not fully develop or cover grey; too much dilutes the dye, so the shade can come out lighter, warmer or patchy and may fade quickly. Measuring both parts with the same scale or measuring bottle avoids most mistakes.

Do I really need an allergy test if I have dyed my hair before?

Yes. Manufacturers and the FDA ask for a skin test before every colouring, because an allergy to dyes such as PPD can appear even after earlier colourings went fine, and reactions tend to get worse each time. Do it 48 hours beforehand, as the instructions say, and do not colour if the test area reacts.

Can I dye my eyebrows or eyelashes with hair dye?

No. The FDA says hair dye must not be used to dye eyelashes or eyebrows because it may cause blindness, and EU hair dye labels carry the same instruction. Leave lashes and brows to products made and sold for them.

How much colour do I need for long or thick hair?

Choose Estimate for me and set the length and thickness: long, thick hair can need two or three times what a short cut does. The range is a starting point, so mix the lower amount first and make a fresh small batch at the same ratio if you run short.