Phosphate buffered saline
PBS Buffer Recipe Calculator
Make 1x PBS from a practical recipe: NaCl, KCl, Na2HPO4, and KH2PO4 per liter, with pH, sterilization, scaling notes, and common mistakes.
Standard 1 L 1x PBS recipe
- NaCl
- 8.0 g/L
- KCl
- 0.2 g/L
- Na₂HPO₄
- 1.44 g/L
- KH₂PO₄
- 0.24 g/L
Preparation steps
- 1Add salts to about 800 mL deionized water and stir until dissolved.
- 2Check pH and adjust to pH 7.4 with HCl or NaOH if required by your protocol.
- 3Bring to exactly 1 L final volume with water, then mix thoroughly.
- 4Autoclave or filter-sterilize through a 0.22 µm filter when sterile PBS is needed.
Worked example
- For 500 mL, multiply each 1 L amount by 0.5: 4.0 g NaCl, 0.1 g KCl, 0.72 g Na₂HPO₄, and 0.12 g KH₂PO₄.
- Dissolve in less than 500 mL, adjust pH, then bring to 500 mL final volume.
Safety and verification
- Use sterile technique for cell culture work; non-sterile PBS can contaminate assays.
- Verify pH after all salts dissolve, especially when changing water source or phosphate salt form.
- Label with concentration, pH, preparation date, and sterilization method.
Common mistakes
- Adding 1 L of water after salts instead of bringing the solution to 1 L final volume.
- Substituting hydrated phosphate salts without recalculating mass.
- Skipping pH verification for protocols that are pH-sensitive.
Frequently asked questions
What pH should 1x PBS be?
Most biology workflows use PBS at pH 7.2–7.4. The LabTools preset targets pH 7.4; verify against your protocol.
Can I scale this PBS recipe?
Yes. Scale each component linearly by final volume, then bring the dissolved solution to final volume.
Is PBS the same as DPBS?
Not always. DPBS formulations may include or omit calcium and magnesium. Check your cell-culture protocol before substituting.
Scale this recipe without spreadsheet drift
Open LabTools for unit-aware solution prep, buffer presets, and protocol-style output.