Formula
pH=pKa+log₁₀([base]/[acid]).
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Concentration approximation for an established weak-acid buffer; not a general acid–base equilibrium solver.
Example Calculation
Example inputs
- pKa: 4.76
- Conjugate-base concentration: 0.1 mol/L
- Weak-acid concentration: 0.1 mol/L
Equal acid and conjugate-base concentrations give pH=pKa=4.76.
Method references
Frequently asked questions
How do I use this calculator?
Enter pka, conjugate-base concentration, weak-acid concentration. The result updates automatically. Use Reset to restore the example values.
What method does it use?
pH=pKa+log₁₀([base]/[acid]).. Concentration approximation for an established weak-acid buffer; not a general acid–base equilibrium solver.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.