Is it OK to leave deep conditioner in overnight?

It is not worth it. A conditioner does its work in the first 20 to 30 minutes, so there is no added benefit after that, and soaking hair for hours can leave it over-soft, limp and weaker when wet. Protein treatments left on for hours can make hair stiff and brittle instead.

Does heat make deep conditioning work better?

Gentle heat helps conditioner spread and soak in faster, which is why the calculator shortens the time when you use a heat cap, hooded dryer or steamer. Keep the setting low to medium, and only use heat with protein or bond treatments if the label calls for it.

How long should low-porosity hair deep condition?

A little longer than average, and with warmth. Low-porosity hair takes product in slowly, so the calculator adds about a quarter to the time. A plastic cap or gentle heat usually helps more than extra minutes. Not sure of your porosity? Try the hair porosity test .

How often should I deep condition?

A moisturizing deep conditioner every wash day to every two weeks suits most textured hair. Light protein every two to six weeks, and strong reconstructors only every six to eight weeks unless the label says otherwise. Too much protein can make hair stiff — the protein or moisture quiz helps you balance the two.

Should I deep condition before or after shampoo?

Moisturizing deep conditioners and most protein treatments go on after shampoo, on clean, damp hair. Hot oil treatments and pre-poos go on before shampoo to soften and protect the strands while you wash. Bond-repair treatments vary, so follow the label.

How Long to Deep Condition Hair? Time Calculator

How long to deep condition hair: how the time is worked out

Conditioners work on the surface of the strand. Their conditioning agents settle onto the cuticle, mostly where it is worn or raised, and that happens within the first part of a session. Extra time adds very little, so the calculator starts from a typical label range for each kind of treatment and then adjusts it for three things you can tell it.

minutes = treatment range × heat × porosity × condition
rounded to 5 minutes, never past the upper limit

The three adjustments

Heat speeds things up: a plastic cap trims the time a little (×0.85), a heat cap or hooded dryer by about a third (×0.67), and a steamer by half (×0.5). Low-porosity hair takes product in slowly, so it gets more time (×1.25); high-porosity hair absorbs fast and gets less (×0.85). Healthy hair needs less (×0.85) and damaged hair gets the long end (×1.15). These factors are rules of thumb, not measured values.

Why protein and bond treatments have a hard stop

Protein treatments and reconstructors are designed for a set time. Left on longer, they can leave textured hair stiff and brittle, which is the opposite of what you want. Bond-repair treatments are also timed by the manufacturer. For these the result always says never longer than the label, and if your label gives a shorter time than the calculator, the label wins.

Why not overnight?

Once the conditioner has settled onto the hair, there is no added benefit to waiting. Hours of soaking keep the strand swollen with water, which can leave it over-soft, limp and easier to stretch and break. If your hair still feels dry after a full session, the answer is usually a different product, a leave-in afterwards, or checking whether you need protein instead — the protein or moisture quiz helps with that.

What the calculator cannot tell you

It does not know your product. Two masks with the same name can be made very differently, so treat the range as a starting point and watch how your hair responds. It also cannot repair damage: conditioning makes hair feel and behave better, but split and broken ends need a trim. To fit deep conditioning into the rest of your wash day, use the wash day routine builder.

Treatment	No heat	Plastic cap	Heat cap / dryer	Steamer	Upper limit
Moisturizing deep conditioner	15–30 min	15–25 min	10–20 min	10–15 min	45 min
Light protein treatment	10–20 min	10–15 min	5–15 min	5–10 min	The label (≤ 30 min)
Strong protein or reconstructor	5–10 min	5–10 min	5–10 min	5–10 min	The label (≤ 20 min)
Bond-repair treatment	10–20 min	10–15 min	5–15 min	5–10 min	The label (≤ 30 min)
Hot oil or pre-poo	20–30 min	15–25 min	15–20 min	10–15 min	60 min

Treatment	How often
Moisturizing deep conditioner	every 2 weeks (healthy) · every wash day, about once a week (damaged)
Light protein treatment	every 6 weeks (healthy) · every 2 weeks (damaged)
Strong protein or reconstructor	every 8 weeks (healthy) · every 6 weeks (damaged)
Bond-repair treatment	once a month (healthy) · every wash day, about once a week (damaged)
Hot oil or pre-poo	every 2 weeks (healthy) · every wash day, about once a week (damaged)

Deep Conditioning Time Calculator

How to use the Deep Conditioning Time Calculator

Pick your treatment

Add your porosity, heat and hair condition

Press “Get my conditioning time”

Start the timer

How long to deep condition hair: how the time is worked out

The three adjustments

Why protein and bond treatments have a hard stop

Why not overnight?

What the calculator cannot tell you

Deep conditioning time chart

How often to repeat each treatment

Frequently asked questions