Chemistry calculator
pH Calculator for Acids and Bases
Calculate pH and pOH from hydrogen ion concentration.
FormulapH = -log10([H+])
Formula
pH formula
This simplified estimate assumes the common 25 C water relationship for pH and pOH.
pH = -log10([H+])
1e-6 mol/L hydrogen ion concentration gives pH 6.
FAQ6 common questions for this calculator.
FAQs
What concentration unit should I use?+
Enter hydrogen ion concentration in mol/L.
What does lower pH mean?+
Lower pH means higher hydrogen ion concentration.
How does the pH Calculator calculate the result?+
For the pH Calculator, it uses the pH formula: pH = -log10([H+]). 1e-6 mol/L hydrogen ion concentration gives pH 6.
What information do I need to use the pH Calculator?+
Enter the hydrogen ion concentration in mol/L. The calculator applies pH = -log10([H+]) and derives pOH using the simplified 25 C water relationship.
How accurate is the pH Calculator?+
The pH result is sensitive to the hydrogen ion concentration because the scale is logarithmic: a tenfold concentration error changes pH by one unit. The pOH value uses the simplified 25 C water relationship shown on the page.
What should I check before using the pH Calculator result?+
Check that hydrogen ion concentration is in mol/L, positive, and written with the intended exponent. Remember that pH and pOH assumptions can change with temperature and non-aqueous contexts.
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How to use the pH Calculator
Calculate pH and pOH from hydrogen ion concentration. The page also explains the pH formula and shows a practical example: 1e-6 mol/L hydrogen ion concentration gives pH 6.
- 1
Enter your details
Enter hydrogen ion concentration, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the pH formula: pH = -log10([H+]).
- 3
Compare scenarios
Change one or more inputs to see how they affect the pH Calculator result before you use the estimate.