Hair Dye Volume Calculator
Find out how many boxes or ml of hair dye you need based on your hair length and thickness.
Avoid running out mid-application.
Why getting the quantity right matters
Running out of hair dye mid-application is one of the most common home colouring mistakes. It results in uneven colour, patchy roots, and visible demarcation lines that are difficult to fix without professional help. Buying one extra box as insurance is always recommended — unused dye cannot be stored once mixed, but an unopened box can be returned or saved.
Standard box contents
A standard box of home hair dye contains approximately 80–100 ml of dye mixed with the developer (activator). For this calculator, 100 ml per box is used as the standard. Semi-permanent or toning products may come in smaller tubes (50–60 ml).
Hair length and thickness guide
Hair length is measured from the roots to the tips:
- Short: above the ears or chin (up to ~15 cm / 6 inches)
- Medium: collar bone to shoulder length (approximately 20–35 cm / 8–14 inches)
- Long: mid-back to waist (35–65 cm / 14–26 inches)
- Very long: below waist (65+ cm / 26+ inches)
Hair thickness (density) describes how many individual strands you have, not the diameter of each strand:
- Fine/thin: you can see the scalp clearly; a ponytail is less than 2 cm across
- Medium: a ponytail is 2–4 cm across
- Thick/coarse: dense, heavy hair; a ponytail is over 4 cm across
Root touch-up vs full application
For a root touch-up only (2–3 cm of regrowth), you typically need 50% or less of the amount required for a full application. This calculator assumes a full, all-over colour application from roots to tips.