What this calculator computes
Reconstitution means adding a measured volume of liquid diluent to a vial of dry, lyophilized material so it becomes a solution of known strength. This calculator takes three inputs and returns that strength in the units a laboratory scale shows. The first input is vial content: the total mass of material in the vial, in milligrams, as printed on the label. The second is diluent volume: how many millilitres of liquid are added to the vial. The third is optional, a target amount to measure out, in milligrams or micrograms.
From the first two numbers it computes concentration, the mass of material in each millilitre of solution, by dividing vial content by diluent volume. It then converts that figure to concentration per unit on a U-100 volume scale, where 100 units equal 1 mL, so each unit is 0.01 mL. If a target amount is entered, it divides the target by the concentration to show the matching volume in millilitres, microlitres and scale units. The calculator is arithmetic only. It does not recommend any amount, and results depend on the label and the volume actually measured.
Three worked examples
- 5 mg vial, 2 mL diluent: 5 ÷ 2 = 2.5 mg per mL. Divided by 100 units per mL, that is 0.025 mg (25 µg) per unit.
- 10 mg vial, 2 mL diluent: 10 ÷ 2 = 5 mg per mL. Divided by 100 units per mL, that is 0.05 mg (50 µg) per unit.
- 30 mg vial, 3 mL diluent: 30 ÷ 3 = 10 mg per mL. Divided by 100 units per mL, that is 0.1 mg (100 µg) per unit.
What the arithmetic does
Concentration is total material divided by final solution volume: C = M / V. With 20 mg of material in 5 mL of liquid, the concentration is 4 mg per mL. The sample volume for a target amount is the target mass divided by that concentration: a 2 mg target at 4 mg/mL is 0.5 mL, which is 500 µL, or 50 markings on a U-100 volume scale.
Counting syringes instead of typing a volume
If you added the liquid with a syringe, you already know the total: five 1 mL syringes of liquid is 5 mL. The “count syringes” option multiplies the number of syringes by the size of each one for you, so you never have to do that multiplication in your head. Strictly speaking, the dissolved material occupies a small extra volume of its own, so the true final volume is a fraction larger than the liquid you added; this simple mode uses the counted liquid volume as the working figure.
Why the fields are worded this way
- Total material (mg) is the amount stated for the whole container, not the amount in one sample.
- Liquid volume (mL) is the volume of the finished solution. When you count syringes, the tool multiplies for you; when you know the total, enter it directly.
- Target sample amount requires an explicit unit. 1 mg is 1000 µg, and switching the unit here converts the value so the physical amount you entered is preserved.
Units and scales
1 mL is 1000 µL. A U-100 scale divides one millilitre into 100 markings, so one marking is 0.01 mL or 10 µL. A volume marking does not turn a peptide mass into an international unit. Here the markings are a volume scale only. Capacity and calibration are separate properties: selecting a 0.3, 0.5 or 1 mL capacity here changes the illustrated barrel and its labelled scale, and nothing about the calculated numbers.
Blends
For a listing that states only a combined milligram figure for two components, the arithmetic above applies to that combined figure. A per-component concentration cannot be calculated without a stated component ratio, and this tool does not assume one.
Limits
- Use it to plan concentrations for your preparation.
- Actual device graduations vary between products. The illustration is a schematic for reading the number , it is not a physical calibration and does not represent any particular device.
- No claim is made about the real capacity of any container, or about how much material is recoverable from it.
- The tool contains no preparation, handling or administration instructions, and no recommended amounts.