Reconstitution Calculator: mg/mL, mL and Units

The method

The three numbers in every reconstitution

Concentration = powder mg ÷ diluent mL

Draw volume = amount ÷ concentration

U-100 units = draw mL × 100

Reconstitution turns a powder into a liquid that can be measured. Whatever the vial holds, whether a research peptide, HCG, a growth hormone product or a laboratory reagent, the arithmetic uses three numbers: the amount of powder on the label, the volume of diluent in the vial, and the concentration that results.

The first two come from the label and the bottle. The third is the one that matters afterwards, because every later measurement is a volume of that liquid. A 5 mg vial mixed with 2 mL holds 2.5 mg/mL; the same vial mixed with 5 mL holds 1 mg/mL. Neither figure is better than the other. They describe two different liquids, and the calculator needs to know which one is in the vial.

People search for a medication reconstitution calculator, a peptide calculator in mg or a dilution calculator for mg/mL, and all three are this same arithmetic. The calculation treats the diluent volume as the final volume, as the charts on this site do. When a label or a pharmacist states a final concentration, enter that concentration directly; it takes priority over the arithmetic.

Two ways in

Concentration mode and Reconstitution mode

The calculator opens in Concentration mode, for a liquid whose mg/mL is already known: a mixed vial, a pharmacy label or a figure worked out earlier. Enter the mg/mL and an amount, and it returns the draw volume and the units.

Reconstitution mode works one step earlier. It takes the powder amount and the diluent volume, works out the concentration itself, then converts the amount to a draw. Both modes give the same draw for the same liquid: a 10 mg vial in 2 mL entered as a vial, and 5 mg/mL entered directly, both put 0.25 mg at 5 units.

Syringe scale

How a U-100 syringe maps mL to units

Insulin-style syringes are marked in units, and on the U-100 scale 100 units is 1 mL. Each unit is therefore 0.01 mL, and a draw volume converts to units by multiplying it by 100.

The three sizes the calculator offers follow the same scale: a 30-unit syringe holds 0.3 mL, a 50-unit syringe holds 0.5 mL and a 100-unit syringe holds 1 mL. A draw larger than the chosen syringe is flagged in the readout.

Units count volume, not amount. Ten units is 0.1 mL in every vial; what those 10 units contain depends on the concentration. At 2.5 mg/mL they hold 0.25 mg, and at 5 mg/mL they hold 0.5 mg. HCG and some growth hormone labels state IU instead of mg; IU is a measure of amount too, and it is a different thing from syringe units.

Label size × diluent volume

Reconstitution chart: mg/mL and units per mg

The chart lists 2, 5 and 10 mg labels against 1, 2, 3 and 5 mL of diluent. Each cell shows the concentration and how many U-100 units one milligram occupies at that concentration. A value above 100 units per mg means one milligram is more liquid than a 1 mL syringe holds.

Concentration and U-100 units per mg, by label amount and diluent volume
Label amount	1 mL diluent	2 mL diluent	3 mL diluent	5 mL diluent
2 mg	2 mg/mL 50 units per mg	1 mg/mL 100 units per mg	0.67 mg/mL 150 units per mg 1 mg is over one 1 mL syringe	0.4 mg/mL 250 units per mg 1 mg is over one 1 mL syringe
5 mg	5 mg/mL 20 units per mg	2.5 mg/mL 40 units per mg	1.67 mg/mL 60 units per mg	1 mg/mL 100 units per mg
10 mg	10 mg/mL 10 units per mg	5 mg/mL 20 units per mg	3.33 mg/mL 30 units per mg	2 mg/mL 50 units per mg

To read another amount, scale the units per mg. At 2 mg/mL one milligram is 50 units, so 0.25 mg is 12.5 units. Doubling the diluent halves every concentration and doubles every unit count, which is why the 1 mL and 2 mL columns differ by exactly a factor of two.

Arithmetic from the label amounts shown, not doses. Diluent mL is treated as the final volume.

Same rule, other direction

Using it as a dilution calculator for mg/mL

A dilution calculator for mg/mL answers the same question from the other side: how concentrated is the liquid once a given volume is in the vial. The amount of powder never changes; only the volume does. More diluent gives a lower mg/mL and more units for any amount, less diluent gives a higher mg/mL and fewer units, and the syringe marks have to be read against whichever liquid is actually in the vial.

The rule holds for labels in IU. HCG at 5,000 IU in 2 mL is 2,500 IU/mL. The calculator accepts IU for the vial and for the amount, and it converts between IU and mg only for compounds whose library entry lists a factor. For somatropin, the HGH IU to mg explainer works that conversion from the label's own IU per mg figure. The peptide calculator does the same arithmetic with the compound library loaded for names and label references.

Calculator details

Reconstitution questions.

What does a reconstitution calculator do?

It divides the powder amount by the diluent volume to get a concentration, then converts an amount into a draw volume in mL and U-100 syringe units. It works for any vial labelled in mg, mcg or IU.

Does it recommend how much diluent to add?

No. The diluent volume is your input. The calculator shows what concentration a volume produces; it does not choose a volume, a dose or a mixing method.

How do I calculate mg/mL after reconstitution?

Divide the milligrams on the label by the milliliters of diluent. A 10 mg vial with 2 mL is 5 mg/mL; with 3 mL it is about 3.33 mg/mL.

How many units is 1 mL on an insulin syringe?

On a U-100 syringe, 100 units is 1 mL, so 1 unit is 0.01 mL. A 30-unit syringe holds 0.3 mL and a 50-unit syringe holds 0.5 mL.

Can I use it for HCG or HGH in IU?

Yes. Enter the vial and the amount in IU and the calculator returns IU per mL, the draw volume and units. Converting between IU and mg needs a compound whose library entry lists a factor.

Before you mix: the guides

This page does arithmetic only. The how to reconstitute peptides guide walks through the numbers step by step, and bacteriostatic water vs sterile water explains the two diluents. For unit conversions without a vial in the picture, the units to mg converter converts syringe units, mL and mg at a known concentration.

From calculation to routine

Track the result in the app.

Set up each vial once, log doses and sites, and keep your schedule together in PinPoint for iOS.

PinPoint app converting a draw volume into U-100 syringe units — PINPOINT / SYRINGE UNIT CONVERSION

Keep exploring

Reconstitution calculator