Buffer Calculator

Use this free online buffer calculator to prepare common laboratory buffers by target pH, strength, salt or hydrate form, and final volume, with pH-suitability guidance and fixed recipes for PBS, TBS, TAE, TBE, SSC, and TE.

Buffer calculator inputs

Type to search or click the field to choose from the buffer list.

References

Sources for acid/base calculations, biological buffer ranges, mixing tables, and reagent molecular weights. Calculations use original Mol Biology Tools code; published mixing tables are distinguished from pKa-based estimates.

  1. Henderson-Hasselbalch acid/base ratio logic: Henderson (1908), acid strength and buffering capacity.
  2. Biological buffer pH ranges: Good et al. (1966), hydrogen ion buffers for biological research.
  3. Enzyme-assay buffer preparation context: Gomori (1955), preparation of buffers for enzyme studies.
  4. Citric acid/trisodium citrate mixing table: Sigma-Aldrich Buffer Reference Center, verified 14 September 2026. The 100 mM reference uses two 0.1 M stocks across pH 3.0-6.2; intermediate values use linear interpolation, with no extrapolation. Sigma cites Dawson et al. (1986), Data for Biochemical Research, third edition. Scaling concentrations does not validate the final pH.
  5. Salt, hydrate, and acid/base molecular-weight checks: PubChem Compound database.
  6. PubChem database background: Kim et al. (2025), PubChem update. Reagent values are stored locally; the calculator does not query PubChem during a calculation.