What is the standard mix ratio for hair colour?

Most UK professional colour brands use a 1:1.5 ratio of colour to developer for 20 and 30 Vol applications (e.g. 60 ml colour to 90 ml developer). Some brands use 1:1 with 10 Vol for deposit-only services and 1:2 with 40 Vol for maximum lift. Always check the manufacturer instruction leaflet inside your specific colour box as ratios can vary between product lines.

How much colour do I need for different hair lengths?

Short hair (up to chin length) typically requires around 40 ml of colour product. Medium hair (chin to shoulder) needs approximately 70 ml. Long hair (shoulder to mid-back) usually requires 100 ml, and very long hair may need 140 ml or more. These are estimates for full-head application; root regrowth services require considerably less — usually 30–50 ml for most lengths.

How long should I process hair colour?

Standard processing time for permanent colour is 30–45 minutes at room temperature. Deposit-only (same level or darker) typically needs 25–35 minutes. Lightening by 1–2 levels with 20 Vol requires 35 minutes. Maximum lift with 40 Vol needs up to 45 minutes. Never exceed 60 minutes, and always perform a skin allergy test 48 hours before any colour service.

Which developer volume should I use?

10 Vol is for deposit-only services, semi-permanent colour and delicate hair. 20 Vol lifts 1–2 levels and is the most commonly used developer for standard permanent colour. 30 Vol lifts 2–3 levels and is suitable for resistant grey coverage. 40 Vol provides maximum lift of 3–4 levels and should only be used on healthy hair. Never use 40 Vol on previously chemically treated or compromised hair.

CutCalcs

Hair Colour Mixing Calculator — Colour, Developer & Processing Time

Calculate precise colour tube amount, developer volume, mix ratio and processing time based on target shade level, current level, developer strength and hair length.

Target Shade Level

Desired level after colouring (1 = black, 10 = lightest blonde)

Current Hair Level

Client's natural or existing colour level

Developer Volume

Select developer strength for the service

Hair Length

Client's hair length to determine colour quantity

How We Calculate This

How the calculation works

Colour amount is determined by hair length using standard professional benchmarks. Developer amount is calculated from the mix ratio for the selected developer volume:

Developer (ml) = Colour (ml) × Mix ratio

Total mix (ml) = Colour + Developer

Mix ratios by developer volume

10 Vol: 1:1 (equal parts)
20 Vol: 1:1.5
30 Vol: 1:1.5
40 Vol: 1:2

Processing times

Deposit/same level: 25–30 min
1–2 levels lift (20 Vol): 35 min
2–3 levels lift (30 Vol): 40 min
Maximum lift (40 Vol): 45 min

Frequently Asked Questions

Related Calculators

Hair Colour Mix Calculator

Calculate precise colour-to-developer ratios for any hair colour formulation.

Developer Ratio Calculator

Work out the correct developer-to-colour ratio for different application types.

Toner Mix Calculator

Calculate toner and developer quantities for post-bleach toning services.

Bleach Mix Calculator

Determine the right bleach powder to developer ratio and total quantity needed.

Colour Correction Calculator

Estimate colour correction steps, products and processing time needed.

Last updated: March 2026

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