Hair Dye & Developer Mix Calculator

Frequently Asked Questions

What ratio should I use for root touch-up?

A 1:1 ratio with 20 vol developer is the standard for root touch-up with most permanent dyes. This gives good colour deposit and 1-2 levels of lift to match slightly grown-out colour. Check your specific brand's instructions as some require 1:1.5.

Can I use leftover mixed dye later?

No. Once dye and developer are mixed, the chemical reaction begins immediately. Unused mixture starts to oxidise and loses effectiveness within 30-45 minutes. Mixed product should be discarded - never store it or try to use it later.

What happens if my ratio is wrong?

Too much developer (high ratio) produces a thin, runny mixture with more lift but less colour deposit - you may end up with patchy, uneven results. Too little developer (low ratio) makes a thick paste that is difficult to apply evenly and may not oxidise properly, resulting in muddy or uneven colour.

What bowl and brush should I use?

A non-metallic (plastic) mixing bowl and a wide tinting brush or colour whisk. Metal bowls react with hydrogen peroxide in the developer, potentially causing skin irritation or altering the colour chemistry.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

Enter the total mixture volume you need and select your dye-to-developer ratio. The calculator splits the total into the correct dye and developer amounts. For example, a 1:2 ratio with 90 ml total gives 30 ml dye and 60 ml developer. The total mixture volume you need depends on hair length and density: short hair typically needs 60-90 ml, medium shoulder-length hair needs 90-120 ml, and long or thick hair may need 120-180 ml or more for full coverage.

Common Dye-Developer Ratios and Uses

1:1 ratio: Standard for most permanent colour applications when you want full coverage and maximum colour deposit. Equal parts colour and developer.

1:1.5 ratio: Some brands (Schwarzkopf, Pravana) use this as their standard. Results in a slightly thinner mixture with marginally lighter lift.

1:2 ratio: Double the developer to colour. Used for lightening and balayage applications where you need a runnier consistency for precise placement and more lift.

1:3 ratio: Very thin consistency used for high-lift blonde formulas or bleach toners. More lift, less deposit.

Developer Volumes and Lift

Developer volume (measured in volumes or percentages) controls how much the hair is lightened before colour deposits. 10 vol (3%): minimal lift, deposits colour with little change to underlying tone - ideal for dark-to-dark or refreshing existing colour. 20 vol (6%): 1-2 levels of lift, the most common developer for permanent colour. 30 vol (9%): 2-3 levels of lift, used for lightening mid-shades. 40 vol (12%): 3-4 levels of lift, used for high-lift blondes - can cause more damage and scalp sensitivity. Never use 40 vol on previously coloured or damaged hair without a strand test first.

How Much Mixture Do You Need

Getting the quantity right prevents waste and ensures full saturation. Short hair (chin length or above): 60-90 ml total. Medium hair (chin to shoulder): 90-120 ml. Long hair (shoulder to bra strap): 120-150 ml. Very long or thick hair: 150-200 ml or more. For root touch-ups only, 60-90 ml is usually sufficient regardless of total length. For a full head balayage or highlights, estimating 30-40 ml per section and counting sections gives a more accurate total. It is better to mix a little extra than to run out mid-application.

Mixing Tips and Safety

Always mix in a non-metallic bowl - metal reacts with the developer and can cause unpredictable results. Use a tinting brush or whisk to blend thoroughly until the consistency is even and there are no streaks of colour or clear developer. Mix only what you need: hair dye begins oxidising immediately and unused mixed product should be discarded after about 30-45 minutes. Do a patch test 24-48 hours before any colour application to screen for allergic reactions, especially with dark permanent dyes containing PPD. Wear gloves and protect clothing and surfaces from staining.

Hair Dye & Developer Mix Calculator

Frequently Asked Questions

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