Buffer Capacity Calculator
Says how well a buffer resists a change in pH.
Buffer capacity
— mol/L per pH
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Largest possible, at pH = pKa — mol/L per pH
Share of the largest — %
Reading this —
The formula
β = 2.303 × C × Ka × [H⁺] ÷ (Ka + [H⁺])²
Buffer capacity is the strong acid or base, in mol/L, needed to shift the pH by one unit. It is greatest when pH equals pKa.
What to watch out for
The figure scales with total concentration, and falls away quickly more than one pH unit from the pKa.
Frequently Asked Questions
What is the capacity of a 0.1 mol/L buffer at its pKa?
0.05756 mol/L per pH unit.
How does capacity change one unit from the pKa?
It falls to 33% of the peak.