Hair dye developer ratio calculator
Most permanent and demi-permanent hair colours are mixed with a developer in a set ratio, such as 1:1, 1:1.5 or 1:2. This hair dye developer ratio calculator turns a ratio and one known amount into the grams (or ounces) of colour and developer to weigh out, and lists the usual developer strengths from 10 to 40 volume.
The ratio and developer for your product come from its instructions; this tool only does the arithmetic. Everything runs in your browser. It is not medical advice or a replacement for a stylist’s consultation.
How to use the Hair Dye Developer Ratio Calculator
- Choose the ratio from the leaflet (1:1, 1:1.5, 1:2 or a custom one).
- Say which amount you know: the total mix, the colour or the developer, and enter it in grams or ounces.
- Weigh out the colour and the developer shown on a kitchen scale.
- Check the strength table to confirm the developer you chose, and mix in a non-metal bowl.
- Do a patch test, and a strand test if you can, before colouring all of your hair.
Hair Dye Developer Ratio Calculator features
Any ratio
Presets for 1:1, 1:1.5 and 1:2, plus a custom developer share.
Three ways round
Start from the total mix, the colour you have, or the developer you have.
Grams and ounces
Switch the unit and both amounts convert.
Volume to percentage
10, 20, 30 and 40 volume developer with the matching 3, 6, 9 and 12% peroxide.
How the ratio maths works
A ratio of 1:1.5 means 1 part colour to 1.5 parts developer, so the colour is 1 ÷ 2.5 = 40% of the mix and the developer 60%. For a total of 100 g that is 40 g and 60 g. If you know the colour, multiply it by the developer part (30 g at 1:2 needs 60 g developer); if you know the developer, divide by it (90 g at 1:1.5 is 60 g colour).
Many professional colours are mixed 1:1. For example, Wella’s Koleston Perfect is mixed with Welloxon Perfect in equal parts, using 6%, 9% or 12% for increasing lift, while its Special Blonde shades take two parts developer; Schwarzkopf’s Igora Royal is also mixed 1:1 with 3%, 6%, 9% or 12% developers (product and distributor guidance, read 19 October 2026). Other brands use 1:1.5 or 1:2, particularly lighteners and some demi-colours, so always follow the instructions on your pack.
| Ratio | Colour share | Developer share | For 90 g of mix |
|---|---|---|---|
| 1 : 1 | 50% | 50% | 45 g + 45 g |
| 1 : 1.5 | 40% | 60% | 36 g + 54 g |
| 1 : 2 | 33% | 67% | 30 g + 60 g |
Developer strength: volume and percent
Developer strength is given as volume (10, 20, 30, 40) or as the percentage of hydrogen peroxide (3, 6, 9, 12%); the percentage is the volume times 0.3. A higher strength lifts more but is harsher on the hair and scalp. Manufacturers differ in how many levels each strength lifts, so use the guidance on the pack rather than the general table on this page. Mixing a stronger developer than the instructions say can damage hair and burn skin.
Safety: patch test and care
Hair colour can cause serious allergic reactions. Manufacturers such as Schwarzkopf advise a patch test about 48 hours before colouring, and instructions for other brands may differ, so follow the leaflet every time, even if you have used the product before. Do not dye eyebrows or eyelashes, wear the gloves supplied, keep the mix away from eyes, rinse thoroughly, and stop and rinse if you feel burning or itching. Seek medical help for swelling or breathing trouble. If you want to track changes in your hair, see the hair growth calculator.
Hair Dye Developer Ratio Calculator FAQ
What is the ratio of hair dye to developer?
It depends on the product. Many permanent colours are mixed 1:1; others use 1:1.5 or 1:2. Follow the instructions on your pack.
How much developer do I mix with 60 g of colour?
At 1:1, 60 g; at 1:1.5, 90 g; at 1:2, 120 g. Choose the ratio and enter the colour amount to check.
What is 20 volume developer in percent?
6% hydrogen peroxide. 10 vol is 3%, 30 vol is 9% and 40 vol is 12%.
Which developer should I use?
The one your colour’s instructions name for the result you want. Lower strengths deposit colour or lift a little; higher ones lift more but are harsher.
Do I need a patch test?
Yes. Manufacturers advise a skin patch test about 48 hours before colouring, every time. Do not colour if you react.
Should I measure by weight or volume?
By weight on a kitchen scale. Creams and developers have different densities, so millilitres and grams are not equal.