What you provide
What you provide
- A positive hydrogen-ion concentration in mol/L
- Acceptance of the ideal concentration approximation and 25 °C pOH convention
CHEMISTRY / CONCENTRATION APPROXIMATION
pH Calculator
Estimate pH from hydrogen-ion concentration and show the corresponding ideal 25 °C pOH and hydroxide concentration with activity limitations.
- 01 Calculated in this tab
- 02 Values stay in this browser tab
- 03 Use boundary
Use boundary
Calculation path
The page applies negative base-10 logarithm to entered hydrogen-ion concentration as an ideal activity approximation. At 25 °C it uses pH + pOH = 14 to show the corresponding hydroxide scale.
Calculation path
Approximate pH = -log10 of hydrogen-ion concentration in mol/L.
What you receive
What you receive
- Concentration-based pH estimate
- Ideal 25 °C pOH and hydroxide concentration
- Logarithmic equation with substituted concentration
Use boundary
Choose the maximum decimal places shown. This does not increase source accuracy.
Formal pH is defined from hydrogen-ion activity. Real measurement requires appropriate standards, calibrated electrodes, temperature handling, and chemical-equilibrium analysis.
Use consistent units and preserve more precision than the displayed result when carrying an answer into another calculation.
Reviewed reference factors