Buffer Capacity Calculator
Estimate how strongly a buffer solution resists pH change by entering its total concentration, pKa, and working pH.
What buffer capacity means
Buffer capacity (often written as the Greek letter beta, β) measures how many moles of strong acid or base per liter must be added to change a buffer’s pH by one unit. A higher value means the solution resists pH changes more strongly.
The formula used
This calculator uses the Van Slyke equation, β = 2.303 × C × Ka × [H+] / (Ka + [H+])², where C is the total buffer concentration, Ka is the acid dissociation constant derived from the pKa you enter, and [H+] is derived from the pH. Buffer capacity is at its maximum when the pH equals the pKa, which is why buffers are typically chosen to work near their pKa.
- Total concentration is the combined molarity of the acid and conjugate base forms.
- pKa is a property of the specific weak acid used.
This tool is intended for general chemistry, lab planning, and educational purposes, not as a substitute for empirical titration of your specific system.