Henna and indigo ratio for dark brown hair

Mix the henna first, allow for its dye-release time, then prepare and add the indigo shortly before applying. Your starting colour and the amount of grey can affect how even the result looks.

The dark brown ratio

For a one-step mix, the dark brown guide is about 25% henna and 75% indigo by powder weight. In simple parts, that is 1 part henna to 3 parts indigo. Measure the powders rather than relying on scoops, since the proportions are easier to keep consistent by weight.

The henna contributes the red-orange dye base, while indigo shifts the result towards brown. This ratio is a starting point, not a promise of an identical shade on every head of hair: the starting colour, grey share and the powders themselves affect the result. Plant dyes cannot lighten hair, so the mixture will not make darker hair lighter.

• For a dark brown target: about 25% henna and 75% indigo.
• Keep notes on the proportions and timing if you want to repeat a result.

How grey hair changes the plan

Consider both the amount of grey and where it is distributed. When grey strands are mixed through darker hair, the finished colour can look less uniform than it does on a single, even-coloured swatch. A higher grey share can also make differences at the roots more noticeable as hair grows.

Use a strand test on a hidden lock or hair clippings that represent your mix of grey and pigmented hair. This gives you a more useful preview than testing only on a dark strand. If you are aiming for a consistent dark brown, judge the test after the colour has had time to deepen, rather than only while the hair is wet or freshly rinsed.

Avoid adding indigo alone to grey or light hair: without a henna base it tends to turn those strands blue or green. The one-step henna-indigo mix is different, but the final shade still varies. If your test is not close to the colour you want, adjust your plan before applying it to your full head rather than assuming the same ratio will suit every starting colour.

Mixing order: henna first, indigo second

Begin with the henna. Its dye-release time varies with the powder and room temperature: some suppliers give about 3–4 hours for their blend, while others suggest leaving it overnight, around 8–12 hours. Follow the instructions for your powder and check dye release with a small dab on your palm or a paper towel; an orange stain indicates that it is ready.

Prepare the indigo shortly before application. Mix it with warm water only, let it rest for about 20–30 minutes, then use it promptly; indigo does not keep once mixed. Add it to the released henna and combine thoroughly so the mixture is consistent. The key is to avoid preparing indigo far in advance while the henna is releasing dye.

Apply the finished mixture according to the product instructions, making sure your test and full application use the same mixing order. Use the same proportions across the batch so that the colour is as consistent as your starting colour allows.

How much powder to prepare

The total powder amount depends on hair length and thickness. The figures below are approximate guidance for medium-thickness hair; thick hair needs more and fine hair less. These are total amounts for the henna-indigo mixture, not the amount of henna alone.

• Divide the total amount using the 1:3 henna-to-indigo ratio.

Application time and colour settling

A common approximate leave-on time for henna mixtures is 2–4 hours. Follow the instructions for your powders and use the same timing for your strand test. Leaving henna on much longer than about 4 hours does not usually increase colour intensity much, so a longer application is not a reliable way to make the result darker.

Rinse according to the product instructions. Henna-indigo colour usually deepens over about 24–48 hours, so the shade immediately after rinsing may not be the final one. Check your test strand after this settling period before deciding how closely the result matches your dark brown target.

Upkeep and a brief safety check

Henna-indigo colour does not wash out like a temporary rinse. It usually fades a little, while dyed lengths grow out. Root touch-ups are often needed every 4–6 weeks, depending on growth and the share of grey; use your test results to guide any repeat application.

Before using any dye, do a patch test 48 hours beforehand behind the ear or on the inner elbow, following the product instructions, and do a strand test on a hidden lock or clippings. Before chemical dye or bleach over henna, test a strand because compound henna can contain metallic salts. “Black henna” for skin often contains PPD. If you have a reaction, rinse it off and seek medical help.