Hair Dye Mixing Calculator

Free Hair Dye Mixing Calculator

Getting the colour-to-developer ratio right matters: too much developer and the colour is weak and runny and fades fast, too little and it will not process properly or cover grey. This calculator does the arithmetic three ways — from a total amount, from the colour you already have, or from your hair length — and tells you how many tubes to buy so you are not left short part-way through.

The three ways to work it out

• By total amount — you know you want, say, 180 ml of mixture. At 1:2 that is 60 ml of colour and 120 ml of developer.
• By colour you have — you have one 60 ml tube and need to know the developer. At 1:1 that is 60 ml, at 1:2 it is 120 ml.
• By hair length — pick your length and thickness and the calculator estimates the colour needed, then works out the developer and the tubes.

Common mixing ratios

Ratios differ between brands and even between lines from one brand, and manufacturers do reformulate. Treat the table as orientation and the tube as the authority.

Which developer strength?

How much dye do I need?

The usual rule of thumb is one 60 ml tube for average shoulder-length hair. Shorter hair needs less, longer or thicker hair needs more, and a root touch-up needs about half a tube. Thick or coarse hair takes noticeably more product than fine hair of the same length, which is why this calculator asks about both. These figures are estimates: porosity, how you section, and how generously you apply all change the real number, so allow a margin.

Mixing tips

• Mix in a non-metallic bowl. Metal can react with peroxide.
• Mix only what you are about to use. Once colour and developer meet, the reaction starts and cannot be paused — leftover mixture cannot be saved for next time.
• Weigh or measure rather than eyeballing it, especially at 1:1.5 and 1:2 where a small error moves the ratio a long way.
• Patch test 48 hours ahead, every time, even with a colour you have used before.
• Wear gloves, and work in a ventilated room.

Related tools

Mixing pigments rather than dye? The paint colour mixing calculator works out what colour two paints make, and the colour code converter converts between HEX, RGB, HSL and more.

A note on safety

This calculator handles the arithmetic only. It is not a substitute for the instructions supplied with your product or for professional advice. Follow the manufacturer's ratio, timing and safety guidance, and if you are attempting a significant change — heavy lifting, colour correction, or working over previously treated hair — see a stylist.

Privacy and Security

We respect your privacy. This tool is a browser-based application, so every calculation happens on your own device. Nothing you enter is uploaded to our servers or stored.