You’ve probably seen “pH” on a water test, a skincare label, or a lab result. It’s a way to describe how acidic or alkaline a water-based solution is. But what do the numbers actually mean?
Understanding the pH scale
The pH scale typically runs from 0 to 14. A pH of 7 is neutral. Numbers below 7 are acidic, and numbers above 7 are alkaline, also called basic.
The scale is logarithmic: a change of one pH unit represents a tenfold change in acidity. That’s why a reading of 5 isn’t just a little more acidic than a reading of 6.
Where does pH matter?
pH helps people understand and monitor everything from soil and swimming pools to foods and laboratory samples. The useful range depends on what you’re testing. There’s no single “best pH” for everything.
For example, gardeners may test soil because its pH affects how readily plants can take up nutrients. Someone testing pool water has a different goal: keeping the water within the range recommended for their pool and treatment products.
How is pH measured?
Common methods include test strips and digital pH meters. Strips are convenient for a quick reading: dip one into the sample, then compare its color with the chart supplied by the manufacturer. A meter gives a numerical reading but needs proper calibration and care.
Whichever method you use, follow the product instructions. Timing, sample handling, and reading the correct color chart can all affect the result.
The takeaway
pH is a useful measurement, but a number only makes sense in context. Know what you’re testing, use a method suited to that sample, and compare the result with guidance for that specific use.
If you’re measuring pH as part of a health test, don’t use the result alone to diagnose a condition. Follow the test instructions and discuss concerns with a qualified healthcare professional.