🧫 pH Calculator
Calculate pH, pOH, and ion concentrations
How pH Calculation Works
Formula
pH = -log₁₀[H+]; pOH = 14 - pH
- 1Enter the hydrogen ion concentration [H+] in moles per liter.
- 2pH is calculated as the negative base-10 logarithm of [H+].
- 3pOH = 14 - pH (at 25°C).
- 4Hydroxide concentration [OH-] = 10^(-pOH).
- 5pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.
About pH Calculator
Calculate pH from hydrogen ion concentration, or find [H+] from pH. Shows pOH, [OH-], and acid/base classification.
Frequently Asked Questions
What does pH stand for?
pH stands for 'potential of hydrogen' (or 'power of hydrogen'). It's a logarithmic scale from 0 to 14 that measures how acidic or basic a solution is.
Why is the pH scale logarithmic?
Each pH unit represents a 10-fold change in hydrogen ion concentration. pH 3 has 10× more H+ ions than pH 4, and 100× more than pH 5. This makes the scale more practical for the huge range of concentrations.
What is the pH of common substances?
Battery acid: pH 0, Lemon juice: pH 2, Coffee: pH 5, Pure water: pH 7, Baking soda: pH 9, Bleach: pH 13, Drain cleaner: pH 14.