Vial strength
The total amount of medication in the vial, such as 5 mg, 10 mg, or another labeled amount.
Reference calculator
Reconstitution calculator
Use vial strength, liquid volume, target dose, and syringe type to check concentration, mL to draw, syringe units, and estimated doses per vial.
* This is math only. It does not choose a dose, choose how much liquid to add, or replace the prescription label, vial instructions, pharmacist, or clinician. It does not give a how-to-reconstitute walkthrough or tell you what bacteriostatic water amount to use.
Enter the label details
Total medication amount listed for the vial.
Use the amount your label or pharmacist told you to add.
The dose you are checking against the vial math.
Units are syringe markings, not medication units.
Example: U-100 means 100 units per mL.
Draw to
40
units
0.4 mL at 5 mg/mL.
Visual draw
U-100 scale
Marker shown at 40 units on a U-100 syringe.
Concentration
5 mg/mL
Volume
0.4 mL
Doses per vial
5
10 mg / 2 mL = 5 mg/mL. 2 mg / 5 mg/mL = 0.4 mL.
What the math means
Four numbers matter
Liquid volume
The amount of diluent listed in your instructions. Do not guess this number from an online example.
Concentration
The vial strength divided by liquid volume. Example: 10 mg in 2 mL becomes 5 mg/mL.
Draw amount
The target dose divided by concentration. If using a unit-marked syringe, mL converts to syringe units.
Before using any result
Check the label, not memory
Match the units
mg, mcg, IU, mL, and syringe units are not interchangeable. The calculator converts mg/mcg/g when possible, but it cannot verify what your vial should be.
Use the instructed liquid amount
The liquid volume controls the final concentration. Changing it changes every draw amount that follows. This page does not tell you how much bacteriostatic water to add.
Confirm syringe type
A U-100 syringe has 100 units per mL. A U-40 syringe has 40 units per mL. The same mL volume appears at different unit markings.
Ask when anything conflicts
If the vial label, prescription, syringe, or calculator result do not agree, pause and ask the pharmacist or clinician before using the medication.
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