🧪 pH Calculator
Acid and base pH from concentration
About this calculator
pH measures how acidic or alkaline a solution is on a 0 to 14 scale. Enter the hydrogen ion concentration and get the pH, or enter a pH and get the concentration back. The calculator also labels the result — strongly acidic, neutral, or alkaline — so the number means something at a glance.
pH equals the negative base-10 logarithm of the hydrogen ion concentration. Because it is logarithmic, each whole pH unit is a tenfold change: pH 3 is ten times more acidic than pH 4 and a hundred times more than pH 5.
Tip: Pure water sits at pH 7 only at 25°C — temperature shifts neutrality slightly, so lab-grade work should note the temperature.