How often do roots need touching up?

Most clients need a root touch-up every 4-6 weeks, when regrowth is approximately 1-2 cm. Clients with grey hair or a stark contrast between natural and coloured hair may want to come in every 3-4 weeks. Some colour techniques like balayage grow out more naturally and can last 8-12 weeks.

How much colour do I need for a root touch-up?

A root touch-up typically needs half the colour of a full head application. For average density hair with 1-2 cm regrowth, approximately 20-30g of colour mixed with an equal amount of developer is usually sufficient. Thicker hair or longer regrowth requires more product.

Should I overlap colour onto previously coloured hair?

Avoid overlapping as much as possible. Overlapping causes colour buildup, making mid-lengths and ends progressively darker and more resistant over time. Apply colour to the regrowth only, then comb through the lengths for the last 5 minutes if refreshing is needed.

CutCalcs

Root Touch-Up Calculator — Regrowth Colour Quantities

Calculate colour and developer quantities for root regrowth applications based on regrowth length and hair density.

Regrowth Length

Typical root touch-up: 1-3 cm

Hair Density

Mixing Ratio

Price Per Tube (optional)

60g tube price for cost estimate

How We Calculate This

This calculator estimates the colour and developer quantities for root applications based on regrowth length and hair density. The formula scales with the amount of new growth.

The formula

Colour = 25g x (Regrowth cm / 1.5) x Density multiplier

Developer = Colour x Ratio

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always perform a strand test before chemical services.