the honest answer about the moon and your hair

no. and we publish a lunar hair calendar every single month, so let me explain why both of those things are true.

Does the moon affect hair growth? There is no published evidence that it does. No controlled trial, no dermatological consensus, not even a small study with a promising signal. And yet women write to me about their hair being in better condition than it has been in years, and they credit the calendar. Both are true at once, and the space between them is the interesting part.

What the evidence on moon phases and hair growth actually shows

Hair grows from the follicle, not the end you can see. Each follicle runs a long growth phase, anagen, lasting two to seven years depending largely on genetics. During it, hair advances at roughly a centimetre a month, about half an inch, and that rate is stubborn.

What moves it: genetics, age, hormones, iron stores, protein, thyroid function, and how much stress your body carried two to three months ago. Hair is a slow reporter. It tells you about a hard season long after it has ended.

Lunar phase does not appear in that literature at all. It has not been tested and found weak. It has never been a variable, which is a different kind of gap and worth naming.

The physics does not help either. The moon moves oceans because oceans are enormous and free to move sideways. The tidal force it exerts on your five litres of blood, held in closed vessels, is smaller than the pull of the wall beside you.

Where the lunar hair calendar actually comes from

This is tradition, and I want to call it that rather than science. The modern version descends from biodynamic agriculture, specifically from Maria Thun, who from the 1950s onward published sowing calendars timing planting to the moon's position through the zodiac. Gardeners carried it into hair. Behind that sit older systems: Vedic muhurta, and the Chinese almanac, the Tong Shu, which assigns auspicious and inauspicious activities to each day and is the source of every feng shui haircut calendar you have seen. So do the Mexican grandmothers I grew up around, who hold firm opinions about waning moons and none about evidence.

They encode centuries of attention to rhythm. What they do not contain is a mechanism. Tradition and proof are different instruments, and a brand that blurs them is asking you to trust it less, not more.

Why the lunar hair calendar still works for the women who use it

Because it is a scheduler with a story attached, and that is the only kind anybody keeps using. Consider what changes when a woman follows one. She oils her scalp on the waxing moon, twice a month, which over two years is fifty oilings she would not otherwise have done. She trims every eight to ten weeks instead of whenever she notices the ends have gone see-through.

None of that is lunar. All of it is consistency, the only thing that has ever reliably changed the condition of anyone's hair. Adherence is the active ingredient, not the calendar. But adherence is boring and the moon is beautiful, and if the beautiful thing gets you to do the boring thing fifty times, I will not call that worthless.

What actually changes how fast your hair grows

• Ferritin, your stored iron rather than the haemoglobin number on a basic panel. Low ferritin is a common finding behind diffuse shedding in women.
• Thyroid function. Both an underactive and an overactive thyroid can thin hair, and hypothyroidism is often missed for years.
• Protein. Hair is largely keratin, and chronic underfuelling shows up there first.
• Hormonal shifts, particularly postpartum and through perimenopause.
• Mechanical load. Tight styles, daily heat and hard brushing damage the hair you already grew, which reads as slower growth because length is lost at the ends.
• Scalp condition. Growth happens in skin, and inflamed skin grows hair poorly.

A note I will always include. I am a designer who has lived inside a thyroid diagnosis, not a doctor, and nothing here is medical advice. If your shedding came on suddenly, is diffuse across the whole head, has not settled after a few months, or arrives alongside exhaustion, cold hands or weight that will not behave, that is a blood test and a doctor rather than a calendar. A moon phase has never diagnosed anything.

How to use a lunar hair calendar without lying to yourself

Use it as a diary, not a mechanism. The waxing half of the month, from new moon to full, is where the tradition puts oiling, washing, and the cut you want to grow back quickly. The waning half is where it puts the cut you want to hold its shape. Our monthly lunar hair calendar lays out the dates, moon phase hair care covers the reasoning, when to cut your hair for growth is there if you only want a date to book, and good days and bad days to cut your hair sets out the four rules that decide any date in any system. For the part of this with some clinical support behind it, the rosemary oil ritual is where I would start.

Common questions about the moon and hair growth

Does the moon affect hair growth?

There is no published evidence that it does. Hair growth rate is governed by follicle biology, genetics, hormones and nutritional status, and lunar phase has never been established as a variable. The moon's tidal force on a human body is negligible.

Is there scientific evidence for the lunar hair calendar?

No. The lunar hair calendar is a tradition, descended from biodynamic sowing calendars and older almanac systems such as the Chinese Tong Shu. It has cultural depth and no clinical trial behind it, and anyone telling you otherwise is selling something.

Does cutting your hair on a waxing moon make it grow faster?

No. Cutting the ends has no effect on follicle activity, on any date. What a trim does is remove split ends, which stops breakage travelling up the shaft, so you keep more of the length you grow. That is as true on a Tuesday in a waning moon as on a full moon.

Why do people say hair cut on a full moon grows back thicker?

Two reasons worth separating. The tradition associates the full moon with fullness, which is symbolic. A blunt fresh end looks and feels thicker than a tapered split one, which is physical. That second effect is real and has nothing to do with the moon.

My hair is thinning. What should I do first?

Get bloods done before you change anything else. Ferritin, a full thyroid panel, vitamin D and B12 cover the most common findings. Sudden, diffuse or persistent shedding deserves a doctor rather than a calendar, and the earlier you look the simpler the answer usually is.

Keep the calendar if it keeps you devoted. Just know what is doing the work.

With love from Bali,
Myrah