Reconstitution Calculator
Calculate the volume of diluent needed to reconstitute a lyophilized (freeze-dried) drug or powder to a desired concentration.
Formula
Volume (mL) = Mass (mg) ÷ Target Concentration (mg/mL)
- Assumes the powder volume is negligible (powder displacement volume ignored).
- If powder displacement is significant, subtract it: V_add = V_final − V_powder.
- Always verify with the drug package insert for exact reconstitution instructions.
500 mg powder → 50 mg/mL
Inputs
- Mass of Powder: 500 mg
- Target Concentration: 50 mg/mL
V = 500 / 50 = 10 mL of diluent needed.
Frequently asked questions
What diluent should I use?
Always follow the drug's package insert. Common diluents: sterile water for injection, bacteriostatic water, or NS.
How do I account for powder volume?
For most drugs the powder volume is small. If given, subtract: Volume_add = Volume_final − Volume_powder.