pH is a measure of the acidity or alkalinity of the scalp and is measured on a scale of 0 to 14. A pH of 7 is normally neutral, while on the scalp that value ranges between 4.5-5.5 on the scale.

The pH of the scalp can be affected by several factors, such as the use of hair products, pollution, stress and diet. An imbalance in the pH of the scalp can cause hair problems, such as dryness, oiliness, flaking, inflammation, disordered microbiome, weakness and hair loss.

Measuring the pH of the scalp can help identify if there is an imbalance in pH and therefore if there are problems with the health of the hair. If the pH is too acidic, the use of specific hair products may be recommended to balance the pH of the scalp. If the pH is too alkaline, it may be necessary to reduce the use of hair products and make diet and lifestyle changes to improve hair health.