How to use the pka and ka calculator
Convert between Ka and pKa. Enter pka in the field above; the ka, acid strength are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- pKa — pKa
Worked example
With pka = 4.76, the calculator gives ka ≈ 1.7378 × 10⁻⁵; acid strength ≈ Weak.
Frequently asked questions
What is the formula for the pka and ka calculation?
Ka = 10^(-pKa). Acid strength = pKa<0?"Very strong":(pKa<4?"Moderately strong":(pKa<10?"Weak":"Very weak")). Here pKa is pka.
What inputs do I need for the pka and ka converter calculator?
You need pka. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.