Reconstitution Calculator

// Reconstitution & Draw — For Research Use Only

Mixing & Measuring,
Made Simple.

New to reconstitution? Most of the confusion comes down to one idea: the powder and the liquid are measured in different ways. Learn it once here — then let the calculator do the math.

// Start Here — The One Idea That Unlocks Everything

Solid vs. Liquid

Peptide powder and bacteriostatic water combining into a reconstituted vial

You start with a dry powder (the peptide) and add a liquid (typically bacteriostatic water). Everything else on this page is just figuring out how much peptide ends up in each pull of the syringe. Get these two units straight and the rest falls into place:

The Solid
mg & mcg

How much peptide you have — a weight. 1 mg = 1000 mcg. Once it dissolves you can’t see it, but it’s still in there.

The Liquid
mL

How much liquid you add (most commonly bacteriostatic water) — a volume. The syringe measures this liquid, not the peptide itself.

// Step 1

Reconstitute — How Much Water?

Tell us what’s in your vial and how much liquid you’re adding. We’ll give you the concentrationHow much peptide is in each millilitre of liquid, written as mg/mL. It’s the bridge between the solid (mg) and the liquid (mL). — the number Step 2 needs.

mg

The amount printed on the vial (the dry powder).

mL

More water = weaker mix (lower concentration). Less water = stronger. Bacteriostatic water is the most commonly used reconstitution solvent; the right choice depends on the compound and protocol.

mL

A 3 mL vial physically holds 3 mL — you can’t add more than it fits.

How much water should I add?

There’s no single “right” amount — it just changes how strong your mix is. Most researchers add 2 mL or 3 mL for a few practical reasons: it’s an easy round number to measure, it fits comfortably inside a standard 3 mL vial, and it keeps the concentration math simple. More water spreads the same peptide thinner (lower mg/mL, so you draw a bit more liquid); less water makes it stronger (higher mg/mL, so you draw less). The amount of peptide never changes — only how much liquid it’s spread through.

—
Enter your vial and water amounts above.

// Step 2

Draw — How Far Do I Pull?

Enter the working amountThe amount of peptide you want to draw into the syringe for your protocol, measured in mcg or mg. you want and pick your syringe. The syringe below moves to show you the exact line to pull to.

Tip: 1000 mcg = 1 mg. Double-check you picked the right unit — it’s a common mix-up.

All insulin syringes use the same scale: 100 units = 1 mL. Bigger sizes just hold more.

Quick reference — units to mL (any U-100 syringe)
5 u = 0.05 mL 10 u = 0.1 mL 15 u = 0.15 mL 20 u = 0.2 mL 25 u = 0.25 mL 30 u = 0.3 mL 40 u = 0.4 mL 50 u = 0.5 mL 100 u = 1.0 mL
Want to do it by hand?

You don’t need the calculator once you see the pattern — it’s two divisions and a glance at the syringe:

  1. Find your concentration. Peptide (mg) ÷ water (mL).  5 mg ÷ 2 mL = 2.5 mg/mL
  2. Find the liquid you need. Working amount (in mg) ÷ concentration.  1 mg ÷ 2.5 mg/mL = 0.4 mL
  3. Read it on the syringe. Multiply mL × 100 for units.  0.4 mL × 100 = the 40 line

Working in mcg? Divide by 1000 first to get mg (e.g. 500 mcg = 0.5 mg), then follow the same steps.

The #1 Mistake

The numbers on the syringe do not tell you how much peptide you have — they only measure liquid. How much peptide sits at each line depends entirely on your concentration from Step 1. Change the water you add, and the same “40 line” holds a different amount of peptide.

// Plain-English Glossary

The Terms, Decoded

mg (milligram)A weight. Measures the dry peptide powder. 1 mg = 1000 mcg.
mcg (microgram)A smaller weight. 1000 mcg = 1 mg. Most working amounts are in mcg.
mL (millilitre)A volume. Measures liquid — the bacteriostatic water you add and what the syringe reads.
Bacteriostatic waterSterile water with a small amount of benzyl alcohol that inhibits bacterial growth — a commonly used reconstitution solvent. The right solvent depends on the compound and research protocol.
ReconstitutionDissolving the dry powder into liquid so it can be measured and drawn.
Concentration (mg/mL)How much peptide is in each millilitre of liquid. The bridge between the solid and the liquid.
Units (insulin syringe)The marks on an insulin syringe. They measure liquid only — 100 units = 1 mL. They do not measure peptide.
Draw / working amountThe amount of peptide you pull into the syringe for your research protocol.

For research use only · Not for human or veterinary consumption
This tool is provided for laboratory reference. These statements have not been evaluated by the FDA.