pH Calculator
Calculate pH, pOH, hydrogen ion concentration, and analyze acid-base solutions
Calculation Mode
Enter as decimal (0.001) or scientific notation (1e-3)
Key Formulas
pH = -log₁₀[H⁺]
pOH = -log₁₀[OH⁻]
pH + pOH = 14 (at 25°C)
[H⁺] × [OH⁻] = 10⁻¹⁴ (Kw)
pH Scale Reference
About pH Calculator - Acids, Bases & Ion Concentrations
Calculate pH, pOH, and ion concentrations for acids and bases. Comprehensive chemistry calculator.
Our **pH Calculator** computes pH, pOH, hydrogen ion [H+], and hydroxide ion [OH-] concentrations. Enter any one value to calculate the others. Supports strong acids/bases and weak acid/base calculations with pKa. For gas-related chemistry, try our Ideal Gas Law Calculator.
Understanding pH is essential in chemistry, biology, medicine, and environmental science. Our calculator provides instant conversions between the various ways to express acidity/basicity, along with educational content about the pH scale and acid-base equilibrium.
The pH scale ranges from 0-14 in aqueous solutions at 25°C. Values below 7 are acidic, 7 is neutral, and above 7 is basic. Our tool handles calculations across the entire scale and explains the underlying chemistry.
Key Features
Why Use This Tool?
Common Use Cases
Chemistry Lab: Calculate solution concentrations.
Biology Research: Understand buffer systems.
Environmental Science: Analyze water quality.
Education: Learn acid-base chemistry concepts.
Technical Information
- pH = -log₁₀[H+] and [H+] = 10^(-pH)
- pH + pOH = 14 (at 25°C)
- Kw = [H+][OH-] = 1×10⁻¹⁴ at 25°C
- For weak acids: pH = ½(pKa - log C)
Related Tools
How to Use
Select what you know (pH, pOH, [H+], or [OH-])
Enter the value
View all related calculations
Explore acid/base classification