PeptideFederation

Reconstitution calculator

Enter what is in the vial, how much water you add and the amount you want per draw. The calculator returns the concentration and the mark on a U-100 syringe. It also works backwards to the water volume, handles blends, and estimates cost.

Vial contents
Diluent
Target amount per draw

Example values are filled in to show how the math works. Replace them with your own figures.

Syringe

Draw to

– units

– mL on a U-100 syringe

Concentration
– mg/mL
Per 1 unit
– mcg
Draws per vial
–
Total in vial
– mcg
What each mark on the syringe holds
UnitsmLContains

The arithmetic

Every result comes from three relationships.

Concentrationvial mg ÷ water mL = mg per mL
Volumetarget mg ÷ concentration = mL
UnitsmL × 100 = units on a U-100 syringe

Worked example: 10 mg dissolved in 2 mL gives 5 mg/mL, or 50 mcg per unit. A 250 mcg target is 0.05 mL, which is 5 units.

Read the seven common calculator mistakes before relying on any result.

Calculator questions

How do I convert milligrams to syringe units?

Divide the vial’s contents by the water volume to get the concentration. Then divide the amount you want by that concentration to get millilitres, and multiply by 100 to get units on a U-100 syringe. Example: 5 mg in 2 mL is 2.5 mg/mL, so 0.25 mg is 0.1 mL, which is 10 units.

What is a U-100 syringe?

An insulin syringe calibrated for 100 units per millilitre. One unit is 0.01 mL. The 0.3, 0.5 and 1.0 mL sizes hold 30, 50 and 100 units.

Does adding more water change how much peptide is in the vial?

No. The total amount stays the same. More water lowers the concentration, so each unit holds less, and you draw more units for the same amount.

Why does my 5 mg vial not seem to contain 5 mg?

Labels usually state gross peptide mass, which includes counter-ions such as acetate or TFA and residual water. Net peptide content is often 70 to 90% of the label. A certificate of analysis that reports net peptide content lets you correct for it. See how to read a COA.

What is the difference between mcg and mg?

One milligram (mg) equals 1,000 micrograms (mcg). Mixing them up is the most common calculator error, and it produces a 1,000-fold mistake.

Is bacteriostatic water the same as sterile water?

No. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth and allows a vial to be entered more than once. Sterile water for injection has no preservative and is intended for single use.

Compound calculators

Preset vial sizes for each compound