Beauty Calculators
Hair dye amount.
Enter your hair length and thickness to get a starting amount of mixed colour: how many grams of colour and developer, and how many tubes to buy. It is a rule-of-thumb estimate, so it adds extra on purpose. Runs in your browser.
Your hair
Amount to mix
Fill the form and press Calculate.
Worked example
Shoulder-length hair, about 20 cm (8 in), medium density, 1 : 1 ratio, 20% extra. The 15 to 25 cm band is 120 g of mixed product. Add 20% for 144 g, rounded to 145 g: 72.5 g of colour and 72.5 g of developer. With 60 g tubes that is 2 tubes of colour.
How it works
The mixed amount for medium density comes from the hair length: up to 8 cm 60 g, up to 15 cm 80 g, up to 25 cm 120 g, up to 35 cm 160 g, up to 50 cm 200 g, up to 70 cm 260 g, longer 320 g. It is multiplied by 0.85 for fine hair or 1.25 for thick hair, then by 1 + the extra you choose, and rounded to the nearest 5 g. The result is split by your colour : developer ratio. Tubes = colour grams / tube size, rounded up.
Roots only: 40 g of mixed product for up to 2 cm of regrowth, scaled up in proportion for longer regrowth, then the same density, extra and ratio steps.
Why an estimate. No manufacturer or standards body publishes how much dye a head takes; it depends on length, density, how saturated the colour is and how generously you apply it. These bands are a TNAADO rule of thumb. Mixing a little extra is cheaper than running out with half your head coloured, but mixed colour cannot be stored, so do not mix more than you can use.
Not medical advice. Hair dye can cause allergic reactions in some people. Always follow the directions printed on your product, do a patch test 48 hours before colouring, and see a doctor if you get a reaction.
Sources and basis (checked 2026-10-05): TNAADO rule-of-thumb length bands; ounce conversion 1 oz = 28.349523125 g (NIST). Use the developer mixing calculator for exact ratio maths once you know the amount.
FAQ
How much hair dye do I need for shoulder-length hair?
About 120 to 150 g of mixed product (colour plus developer) with this tool, which is roughly two 60 g tubes of colour at a 1 : 1 ratio. Use more for thick hair and less for fine hair.
How much hair dye do I need for long hair?
Hair 50 to 70 cm long (past the middle of the back) lands around 260 g of mixed product for medium density, so plan on about three 60 g tubes at 1 : 1, and four or more for thick hair.
How much dye do I need for a root touch-up?
Up to 2 cm of regrowth takes about 40 g of mixed product at the base amount, then scales with the regrowth length. Enter the regrowth in the roots-only mode.
Should I buy extra dye?
It is better to have a little extra than to run out part-way, which leaves uneven colour. The tool adds 20% by default; set it to 0 if you want the bare estimate.
Is this an official amount?
No. Manufacturers do not publish one amount for every head. This is a rule of thumb, so check the directions on your box or tube first.