Why pH Matters When Making Your Own Skincare, Bath & Body Products

When creating your own skincare, bath and body products, one of the most important factors to understand is pH. Even the most luxurious ingredients can perform poorly—or even cause irritation—if the pH of your product is not correct.

Whether you’re making a face cleanser, toner, lotion, shampoo or body wash, checking and adjusting the pH should always be part of your formulation process.

What Is pH?

pH stands for “potential of hydrogen” and measures how acidic or alkaline a product is. The pH scale ranges from 0 to 14.

pH 0–6.9 = Acidic
pH 7 = Neutral
pH 7.1–14 = Alkaline

The lower the number, the more acidic the product. The higher the number, the more alkaline it is.

Why Does pH Matter?

Your skin has a natural protective barrier called the acid mantle, which typically has a pH between 4.7 and 5.5. This slightly acidic environment helps:

Protect against harmful bacteria.
Maintain healthy skin.
Reduce moisture loss.
Support the skin’s natural barrier.

Using products with an unsuitable pH can disrupt this barrier, leading to dryness, irritation, redness and increased sensitivity.

Different Products Need Different pH Levels

Here are some general guidelines:

Facial cleansers: pH 4.5–5.5
Face creams and lotions: pH 5.0–5.5
Body lotions: pH 5.0–6.0
Shampoos: pH 4.5–5.5
Conditioners: pH 4.0–5.0
Body wash: pH 5.0–5.5
Liquid hand wash: pH 5.0–6.0

Active Ingredients Depend on pH

Many cosmetic ingredients only work effectively within a specific pH range.

For example:

Niacinamide: pH 5.0–7.0
Salicylic Acid: Best around pH 3.0–4.5
Glycolic Acid: Typically pH 3.5–4.0
Lactic Acid: Usually pH 3.5–4.5
Vitamin C (L-Ascorbic Acid): Around pH 2.5–3.5

If the pH is too high or too low, these ingredients may lose effectiveness or become unstable.

Preservatives Also Have pH Limits

Many preservatives only work within certain pH ranges. If the pH falls outside their recommended range, your product may not be adequately protected against bacteria, mould and yeast.

Always check the manufacturer’s recommended pH range for your chosen preservative.

Can You Judge pH by Looking at a Product?

No.

A product can look, smell and feel perfect while having an unsafe pH. The only reliable way to know is by testing it with:

A calibrated digital pH meter (most accurate)
High-quality pH test strips (less accurate but useful for some products)

How Do You Adjust pH?

If your product’s pH is too high, you can lower it by adding small amounts of a suitable acid solution, such as:

Citric Acid Solution
Lactic Acid

If the pH is too low, you can carefully raise it using:

Sodium Hydroxide Solution
Arginine (in some formulations)

Always make adjustments gradually, mixing thoroughly and testing after each addition.

What About Soap?

Cold process and hot process soap are different from skincare products.

True soap naturally has a high pH, typically between 9 and 10.5. This is a normal result of the saponification process. Attempting to lower the pH of true soap with acids can damage the soap and should not be done. Instead, ensure the soap has fully saponified, cured properly, and is made with the correct lye calculations.

Synthetic detergent bars (syndet bars), however, can be formulated at a skin-friendly pH.

Make pH Testing Part of Every Batch

No matter how experienced you become, never skip pH testing. It is one of the simplest yet most important quality control steps you can take.

By checking and adjusting the pH of your products, you help ensure they are:

Gentle on the skin
Effective
Stable
Compatible with active ingredients
Compatible with preservatives
Safe for everyday use

A few minutes spent testing pH can make the difference between a product that performs beautifully and one that disappoints your customers.

Happy formulating!