Reconstitution calculator

How to use it

1. Amount in the vial. Enter the figure on the vial label.
2. Unit. Pick mg, mcg or IU beside it, to match the label.
3. Water added. Enter how many mL of diluent went into the vial.

Results appear once both fields hold a number above zero. The panel shows the concentration per mL, the amount in 10 units (0.1 mL) and the amount in one unit (0.01 mL). Results in mg also show the mcg figure beneath them, and results in mcg show mg. IU stay in IU. The formula with your own numbers sits under the panel, and Clear starts over.

Use this calculator to learn what each mL or each syringe unit of a mixed vial holds. To go from an amount you want to measure to a volume and a syringe reading, use the peptide calculator.

The formula

• Concentration per mL = amount in the vial / water added (mL)
• Per 10 units = concentration per mL × 0.1 mL
• Per unit = concentration per mL × 0.01 mL
• 1 mg = 1,000 mcg, for the second figure under mg and mcg results

The 0.1 and the 0.01 come from the U-100 scale, where 100 units fill 1 mL.¹⁰ Rearranged, the first line answers the planning question before a vial is mixed:

• Water to add (mL) = amount in the vial / target concentration per mL

Worked example

The figures below are made up to show the division; they describe no particular product.

A vial labeled 6 mg, mixed with 3 mL.

• Concentration = 6 mg / 3 mL = 2 mg per mL (2,000 mcg per mL)
• Per 10 units = 2 mg × 0.1 = 0.2 mg (200 mcg)
• Per unit = 2 mg × 0.01 = 0.02 mg (20 mcg)

Planning the same vial at 1.5 mg per mL. Water to add = 6 mg / 1.5 mg per mL = 4 mL. Entered in the calculator, 6 mg and 4 mL give 1.5 mg per mL, so 10 units then hold 0.15 mg (150 mcg) and one unit holds 0.015 mg (15 mcg).

A vial labeled 2,000 IU, mixed with 4 mL. Concentration = 2,000 IU / 4 mL = 500 IU per mL, so 10 units hold 50 IU and one unit holds 5 IU.

Choosing the volume of diluent

No single volume is right for every vial. The bacteriostatic water label leaves the volume to the maker of the drug being mixed.¹ An approved product's label fixes it: the EGRIFTA WR (tesamorelin) label calls for 1.3 mL of bacteriostatic water per vial and states the result as 8 mg per mL.³ The same label says the two tesamorelin versions differ in dosage, mixing instructions and storage and are not substitutable, so figures do not carry over even between versions of one drug.³

Without a label, the volume is a trade-off, and the calculator shows both sides of it:

• Less water gives a stronger solution. Each unit mark holds more, so a small amount takes up only a few marks.
• More water gives a weaker solution. The same amount spreads over more marks, but a large amount may no longer fit a small barrel.
• Even numbers are easier to check by hand. A volume that divides cleanly into the amount, such as 2 mL for a 10 mg vial (5 mg per mL), gives round figures.

Whatever you choose, measure the diluent rather than estimating it: the result is only as exact as the volume you type.

What the result assumes

The calculator divides the number printed on the label and treats all of it as peptide, which may overstate what the vial holds. Bachem, a peptide manufacturer, says research peptides are typically more than 95% pure by HPLC, yet the solid may be only 70 to 90% peptide, because it also holds counter-ions (such as acetate or trifluoroacetate) and residual moisture. It adds that peptide content has to be taken into account when making a solution of a set concentration.⁵

The effect is proportional. If a 10 mg vial held 8 mg of peptide, 2 mL of water would give 4 mg per mL, not 5, and every per-unit figure would be 20% lower. Whether a label states net peptide or powder weight is a question for the batch's paperwork; certificates of analysis are covered on the lab results page.

Supplies and guides

The reconstitution guide covers the mixing itself, step by step. Bacteriostatic water has its own supply page, and insulin syringes carry the unit marks that the per-unit results refer to; confirm their scale first. The rest of the lab supplies are on the supplies page.

Some compounds have their own pages on what is known about mixing them, such as TB-500 and AOD-9604. The storage guide covers keeping vials before and after mixing.