Henna and indigo ratio for jet black hair

For jet black hair, use a two-step application: 100% henna first, then 100% indigo, ideally immediately and within about 72 hours.

The henna creates the base for the indigo. A one-step blend combines the powders and usually gives a brown result rather than black.

The ratio for a black result

For the two-step method, the ratio is not a henna-indigo blend. Use 100% henna for the first application, rinse it out, then use 100% indigo for the second. Keep the powders separate so each step can be applied on its own.

The gap between steps matters: apply the indigo ideally right after rinsing the henna and within about 72 hours. If you need to wait, keep within that window where possible. Follow the instructions for each powder, particularly for mixing and application.

This is the method intended to create black with henna and indigo. It is not a guarantee of an identical shade on every head of hair; plant-dye results can vary, so use a strand test to preview the result.

How much henna powder to prepare

The amounts below are approximate henna powder amounts per application for medium-thickness hair. They are a guide for the first step, not a combined henna-and-indigo total. Thick hair may need more and fine hair less. Make enough mixture to cover the hair thoroughly, and check the powder instructions for preparation details.

Prepare each step separately

Henna dye release varies with the powder and room temperature. Some suppliers advise about 3–4 hours for their blend, while others suggest leaving it overnight, about 8–12 hours. Follow the powder’s own instructions rather than assuming one timing suits every henna.

You can check for dye release with a small dab on your palm or a paper towel: an orange stain indicates it is ready. Once prepared, apply the henna and leave it on for about 2–4 hours as common practice; more time does not usually add much colour beyond about 4 hours.

For the second step, mix indigo with warm water only. Let it rest for about 20–30 minutes, then use it promptly: mixed indigo does not keep. Apply it after rinsing the henna, following the product instructions for application and removal.

Why one-step mixes usually look brown

A one-step method mixes henna and indigo together, so it is a different approach from applying each powder separately. The common one-step ratios are designed for brown shades: about 70% henna and 30% indigo for reddish brown, 50/50 for brown, and about 25% henna with 75% indigo for dark brown.

Even a one-step mix with a high proportion of indigo is not the standard method for black. The two-step approach uses pure henna first and pure indigo second. Indigo alone, without a henna base, tends to turn grey or light hair blue or green.

If you have already used a one-step mix and the result is brown, changing the proportions next time may shift the shade towards dark brown, but the black method remains the separate two-step application.

What to expect after colouring

Henna-indigo colour usually deepens over about 24–48 hours, so the shade immediately after rinsing may not be the settled result. Give it that time before judging the final colour, and compare it with the strand test if you made one.

Some people may need repeat indigo sessions to reach or maintain the desired black result. The outcome depends on the particular powders and the starting hair colour, so avoid assuming one application will look exactly like a reference swatch. A hidden-lock test helps you decide whether the shade and process suit your hair.

Henna is effectively permanent: it may fade a little, but it grows out rather than washing out. For henna-indigo colour, root touch-ups are often needed every 4–6 weeks; the interval varies with how visible the roots are and the share of grey.

Safety and compatibility

Patch test 48 hours before use, behind the ear or on the inner elbow, following the product instructions; also do a strand test on a hidden lock or hair clippings. A strand test is especially important before using chemical dye or bleach over henna, because compound henna can contain metallic salts that may react badly.

Pure henna is not the same as products labelled “black henna”: black henna for skin often contains PPD, an ingredient in coal-tar hair dye that can cause serious skin reactions. In the US, henna is approved by the FDA as a hair dye, not for direct skin use.