pH Calculator
Calculate pH from hydrogen ion concentration
About the pH Calculator
pH measures how acidic or basic a solution is, calculated as the negative logarithm of hydrogen ion concentration (pH = -log₁₀[H⁺]). The pH Calculator converts between pH, pOH, hydrogen ion concentration [H⁺], and hydroxide ion concentration [OH⁻], supporting scientific notation for very small concentrations typical in chemistry.
Students solve acid-base chemistry problems, chemists analyze solution properties, and environmental scientists monitor water quality. The calculator also classifies solutions as strongly acidic, weakly acidic, neutral, weakly basic, or strongly basic based on the pH value.
Because calculations run entirely in your browser using JavaScript, you can solve chemistry problems without any data leaving your device. The tool handles the logarithmic calculations automatically and displays results in both decimal and scientific notation.
How to Use the pH Calculator
- Select what you want to calculate from the dropdown: [H⁺] concentration, [OH⁻] concentration, pH, or pOH.
- Enter the known value in the input field using decimal or scientific notation.
- Click Calculate to solve for all related values automatically.
- View the results showing pH, pOH, both ion concentrations, and the acid/base classification.
- Copy any result to your clipboard using the copy buttons next to each value.
Why Use ToolForge’s pH Calculator
- pH calculations execute entirely in your browser using JavaScript—no data is transmitted to any server, ensuring your chemistry work remains private.
- Calculates all related values (pH, pOH, [H⁺], [OH⁻]) from a single input, saving time compared to manual logarithmic calculations.
- Handles scientific notation automatically for the very small concentrations typical in chemistry (10⁻⁷ M, 10⁻¹⁴ M, etc.).
- Provides acid/base classification (strongly acidic to strongly basic) to help interpret the practical meaning of pH values in real-world applications.
Frequently Asked Questions
What is the pH formula?
The pH formula is pH = -log₁₀[H⁺], where [H⁺] is the hydrogen ion concentration in moles per liter (M). pH measures how acidic or basic a solution is on a logarithmic scale from 0 to 14.
What is the pH scale?
The pH scale ranges from 0 to 14. A pH of 7 is neutral (pure water), below 7 is acidic (lower is more acidic), and above 7 is basic (higher is more basic). Each unit represents a tenfold change in hydrogen ion concentration.
What is the relationship between pH and pOH?
pH and pOH are related by the equation pH + pOH = 14 at 25°C. pOH measures the hydroxide ion concentration using pOH = -log₁₀[OH⁻]. This relationship comes from the water autoionization constant Kw = [H⁺][OH⁻] = 10⁻¹⁴.
Can I calculate ion concentration from pH?
Yes, you can calculate hydrogen ion concentration from pH using [H⁺] = 10^(-pH). The calculator also automatically calculates the complementary [OH⁻] concentration using the water autoionization constant.
Why is the pH scale logarithmic?
The pH scale is logarithmic because hydrogen ion concentrations in solutions vary over many orders of magnitude. A logarithmic scale compresses this range into manageable numbers (0-14) while preserving the relative differences between solutions.
