Buffer Recipe Calculator
Calculate the required concentrations and molar amounts of weak acid and conjugate base components using the Henderson-Hasselbalch equation.
Buffer System properties
Specify acid pKa, target pH, concentration, and volume.
Required Base / Acid Ratio
* Ratio of [conjugate base] to [weak acid].
Expert Tip
Buffers work best when target pH is within ±1 unit of the weak acid's pKa. Outside this range, the buffer capacity is rapidly exhausted.
Methodology & Henderson-Hasselbalch
Henderson-Hasselbalch Equation
The relationship between pH, pKa, and component concentrations is governed by:
Stoichiometric Breakdown
Solving the Henderson-Hasselbalch equation yields:
- Ratio (R) = 10^(pH - pKa)
- [Acid] = Total Strength / (R + 1)
- [Base] = Total Strength * R / (R + 1)
How to Calculate Buffer Recipes (Henderson-Hasselbalch)
Designing buffers requires balancing a weak acid and its conjugate base to achieve a target pH:
Identify Buffer pH, pKa and Total Concentration (C)
Find the target pH, the acid dissociation constant (pKa), and total buffer strength.
Calculate Ratio (R)
Solve R = 10^(pH - pKa) = [conjugate base] / [weak acid].
Determine Individual Concentrations
The weak acid concentration is C / (1 + R). The conjugate base concentration is C × R / (1 + R).