What Is Skin pH? Acid Mantle, Balance & Best Products
Your skin is naturally slightly acidic — here's what that means, why it matters, and how to keep it balanced.
Author
askINKEY skincare advisor
Published
10 September, 2026
Time to read
4 minutes
What is skin pH?
The pH scale measures how acidic or alkaline something is, from 1 to 14. Anything from 1–6 is acidic, 7 is neutral, and 8–14 is alkaline.
Healthy skin isn't neutral. It sits on the acidic side, at roughly pH 4.7 to 5.75 — most often quoted as around 5.5. That slight acidity isn't an accident. It's what keeps your skin working properly.
Meet your acid mantle
That faintly acidic film on the surface of your skin has a name: the acid mantle. It's a thin layer of sweat, natural oils and fatty acids, and it's your skin's first line of defence.
A healthy acid mantle helps your skin hold onto water, keeps your skin microbiome happy, and makes it harder for irritants to take hold. It works alongside your skin barrier — the acid mantle is the outermost part of that system.
When it's disrupted, the barrier underneath struggles too. That's when skin feels tight, looks red, or turns dehydrated.
What throws your skin's pH off balance?
Cleansing. The biggest factor. Traditional bar soap can sit at pH 9 or 10. That "squeaky clean" feeling is your acid mantle being stripped.
Water. Tap water is around pH 7, and hard water pushes higher.
Over-exfoliating. Acids have their place, but too much too often doesn't give skin time to recover.
Environment. Pollution, sun exposure and seasonal changes all take a toll.
Your skin itself. Oily skin and sensitive skin sit at different points on the scale, and pH shifts naturally with age.
Skin self-corrects — but it takes time. Every time you strip it, there's a window where it's more vulnerable.
Signs your skin's pH may be off
Tightness after washing. Persistent redness or stinging. Flaking alongside oiliness. Skin suddenly reacting to products it was previously fine with. Breakouts that don't respond to your usual routine.
None of these only mean pH — but if several appeared after a new cleanser, that's a strong clue.
How to choose a pH balanced cleanser
Cleansing is where you have most control, so start here. Look for something formulated close to skin's own pH, and avoid traditional soap on your face. If your skin feels tight afterwards, the cleanser is too harsh — full stop.
Glycerin Gentle Purifying Cleanser — £14
A gentle gel cleanser leaving skin cleansed, balanced and fresh rather than stripped. Glycerin draws moisture in while it cleanses.
Oat Cleansing Balm — £15
For makeup and SPF. Melts everything in 30 seconds without scrubbing. Pair the two for a double cleanse.
Supporting your skin after cleansing
Ectoin Hydro-Barrier Serum — £16
Ectoin is clinically proven to strengthen the skin barrier while deeply hydrating.
Bio-Active Ceramide Moisturiser — £20
Ceramides help hold your barrier together. Clinically proven to repair and strengthen the skin barrier from first use, with 24-hour hydration.
Exosome Glow Serum — £20
If skin looks stressed and dull, this is a hydrating glow serum with 6-in-1 skin rejuvenation — clinically proven to visibly improve radiance, hydration, tone, firmness, elasticity and texture.* In-vitro testing of Cica Exosomes showed a 55% reduction in pro-inflammatory markers and a 63% increase in markers associated with skin renewal after 8 hours.*** Proven to deliver up to 12 hours of hydration** and helps support natural collagen production. 100% saw more glowing skin, clinically proven.* Learn more about exosomes.
What about acids?
Acids aren't the enemy — they're formulated at a low pH deliberately, because that's how they work. The issue is frequency, not existence.
If your skin is already struggling, PHAs are gentlest. The PHA Toner (£14) exfoliates while hydrating.
Don't stack actives — our guide on ingredients you shouldn't mix covers what to avoid.
*4-week clinical study of 26 people. **Clinical study of 31 people. ***In-vitro testing of Cica Exosomes showed a 55% reduction in pro-inflammatory markers and a 63% increase in markers associated with skin renewal after 8 hours.
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