pH Calculator
Calculate pH and pOH from hydrogen-ion or hydroxide-ion concentration with a fast chemistry calculator.
Use pH = -log10[H+] when the hydrogen-ion concentration is known.
Concentration in moles per liter, such as 1e-7 for neutral water.
7
7
Neutral
About the ph calculator
How this calculator works
pH calculations are compact in theory, but it still helps to see pH, pOH, and solution type together instead of working from the logarithm by hand.
This page supports the two most common starting points, hydrogen concentration and hydroxide concentration, in one chemistry-focused calculator.
Where it is useful
It is useful for chemistry homework, quick lab checks, and sanity-checking concentration values against expected acidity or basicity.
Because it needs formula logic, multiple outputs, and mode switching, it is a much better fit for the calculator registry than for text tools or pair converters.
- Calculate pH from hydrogen-ion concentration.
- Calculate pH from hydroxide concentration and see pOH at the same time.
- Interpret whether a solution is acidic, neutral, or basic more quickly.
Example calculations
3 examples[H+] = 1e-7 mol/L
pH 7, neutral
[H+] = 1e-3 mol/L
pH 3, acidic
[OH-] = 1e-2 mol/L
pH 12, basic
Common uses
3 ideas- Calculate pH from hydrogen-ion concentration.
- Calculate pH from hydroxide concentration and see pOH at the same time.
- Interpret whether a solution is acidic, neutral, or basic more quickly.
FAQ
3 answersWhat formulas does the pH calculator use?
When hydrogen-ion concentration is known, the calculator uses pH = -log10[H+]. When hydroxide concentration is known, it uses pOH first and then converts to pH.
Why does the pH calculator require a positive concentration?
The concentration must be greater than zero because the logarithm of zero or a negative number is undefined.
Does the calculator explain what the pH value means?
The result labels the solution as acidic, neutral, or basic based on the pH value, which helps make the number easier to interpret quickly.