pH Calculator

pH is a measure of the acidity or basicity of a solution. It is calculated using the formula: pH = -log₁₀[H⁺], where [H⁺] is the hydrogen ion concentration in moles per liter. pH values range from 0 (most acidic) to 14 (most basic), with 7 being neutral.

pH measures hydrogen ion concentration, while pOH measures hydroxide ion concentration. They are related by the equation: pH + pOH = 14. If you know one, you can calculate the other. A solution with low pH (high [H⁺]) will have high pOH (low [OH⁻]).

Solutions are classified based on their pH: Acidic solutions have pH < 7 (excess H⁺ ions), Neutral solutions have pH = 7 (equal H⁺ and OH⁻ ions), and Basic (alkaline) solutions have pH > 7 (excess OH⁻ ions). The farther from 7, the stronger the acidity or basicity.

Use the formula: pH = -log₁₀[H⁺]. For example, if [H⁺] = 0.001 M (or 1 × 10⁻³), then pH = -log₁₀(0.001) = 3. Simply select "H⁺" mode in the calculator and enter the concentration value.

Yes! Use the formula: pOH = -log₁₀[OH⁻]. You can also use pH since pH + pOH = 14. Select "pOH" or "OH⁻" mode in the calculator depending on what value you have.

Ion concentrations are typically expressed in molarity (M), which is moles per liter. For the calculator, enter positive numbers greater than 0. For hydrogen and hydroxide ions from water autoionization, typical values range from 10⁻¹⁴ to 10⁰.

The calculator uses scientific notation (like 1.23e-7) for very small or very large ion concentrations. This is the standard way chemists express these values. You can enter numbers in regular or scientific notation.

Battery acid: pH ~0, Lemon juice: pH ~2, Vinegar: pH ~3, Pure water: pH 7, Baking soda: pH ~8.3, Ammonia solution: pH ~11, Liquid bleach: pH ~13. These vary based on concentration and conditions.

Yes! pH is important in biology (body pH regulation), medicine (blood pH monitoring), environmental science (water quality testing), food science (fermentation), agriculture (soil pH testing), and many industrial processes.

In aqueous solutions, H⁺ ions are actually hydrated and exist as H₃O⁺ (hydronium ions). However, in pH calculations, we use [H⁺] concentration as a convenient representation. The calculator treats [H⁺] and [H₃O⁺] as equivalent concentrations.

The calculator provides results accurate to three decimal places for pH and pOH values, which is sufficient for most educational and practical purposes. For very dilute solutions (outside 0-14 pH range), standard pH theory has limitations, which the calculator accounts for.

This calculator performs basic pH/pOH calculations for strong acids and bases. For buffer solutions, the pH calculation is more complex and requires the Henderson-Hasselbalch equation. This calculator provides initial reference values but may not be accurate for buffer systems.