pH Calculator Formula
Understand the math behind the ph calculator. Each variable explained with a worked example.
Formulas Used
pH
ph_value = -log10(h_conc)pOH
poh_value = 14 - (-log10(h_conc))Variables
| Variable | Description | Default |
|---|---|---|
h_conc | Hydrogen Ion Concentration [H+](M) | 0.001 |
How It Works
How to Calculate pH
Formula
pH = -log10([H+])
pH ranges from 0 (very acidic) to 14 (very basic). pH 7 is neutral.
Worked Example
Find the pH of a solution with [H+] = 0.001 M.
h_conc = 0.001
- 01pH = -log10(0.001)
- 02pH = -log10(10^-3)
- 03pH = 3
Frequently Asked Questions
What does pH measure?
pH measures the acidity or basicity of a solution. It is the negative base-10 logarithm of the hydrogen ion concentration.
What is the pH scale range?
Typically 0 to 14 for aqueous solutions at 25 C. Values below 7 are acidic, above 7 are basic.
Can pH be negative?
Yes, for very concentrated strong acids where [H+] > 1 M.
Learn More
Guide
pH and pOH Guide
Understand pH, pOH, and the pH scale. Learn how to calculate pH from hydrogen ion concentration, the relationship between pH and pOH, buffers, and real-world applications.
Ready to run the numbers?
Open pH Calculator