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Research Peptides & Wellness

Peptide Reconstitution Calculator

Tap three answers below — we'll show you exactly where to fill your syringe.

Step 1: Pick your vial
mg
Step 2: How much water did you add?
mL
Step 3: How much are you measuring out?
mg
1 mg = 1,000 mcg — same amount, just a different ruler. mg is the default because that's how most people in the US think of it.
Fill your syringe to:
— units
= — mL · — mg/mL · about — doses in the vial
That's more than one full syringe — a full syringe is 100 units.

Quick-Reference Chart

What you get with common vial sizes and water amounts. The second number in each box is mcg per syringe unit (U-100).

Vial 1 mL water 2 mL water 3 mL water
2 mg 2.00 mg/mL20 mcg/unit 1.00 mg/mL10 mcg/unit 0.67 mg/mL6.7 mcg/unit
5 mg 5.00 mg/mL50 mcg/unit 2.50 mg/mL25 mcg/unit 1.67 mg/mL16.7 mcg/unit
10 mg 10.00 mg/mL100 mcg/unit 5.00 mg/mL50 mcg/unit 3.33 mg/mL33.3 mcg/unit
20 mg 20.00 mg/mL200 mcg/unit 10.00 mg/mL100 mcg/unit 6.67 mg/mL66.7 mcg/unit

How the Reconstitution Math Works

Reconstitution means adding a measured volume of water to a vial of freeze-dried (lyophilized) powder so it becomes a liquid with a known concentration. Once you know the concentration, every other number on this page is simple arithmetic. There are really only three ideas behind the whole calculator: concentration, syringe units, and unit conversion.

1. Concentration. Concentration is the amount in the vial divided by the water you added:

Concentration (mg/mL) = vial amount (mg) ÷ water added (mL)

A 10 mg vial mixed with 2 mL of water gives 10 ÷ 2 = 5 mg/mL. The same vial mixed with 1 mL gives 10 mg/mL — twice as concentrated, because the same amount is dissolved in half the liquid. The total amount in the vial never changes; only how spread out it is.

2. Syringe units. This calculator assumes a standard U-100 syringe, where 100 units = 1 mL and 1 unit = 0.01 mL. So the amount in one unit is simply the concentration divided by 100. At 5 mg/mL, one unit holds 0.05 mg — which is 50 mcg. That “mcg per unit” figure is the key conversion: to find how many units to draw for a given amount, divide the amount (in mcg) by the mcg per unit.

3. Measurements per vial. Divide the total amount in the vial by the amount in one measurement, using the same unit for both. A 10 mg vial holds 10,000 mcg, so measurements of 250 mcg each give 10,000 ÷ 250 = 40 measurements per vial. The calculator rounds this down to whole measurements.

Milligrams and Micrograms, Explained

Milligrams (mg) and micrograms (mcg) both measure mass — they are just different-sized rulers for the same thing. One milligram equals 1,000 micrograms, so converting is a matter of moving the decimal point three places: multiply mg by 1,000 to get mcg, or divide mcg by 1,000 to get mg. For example, 0.25 mg = 250 mcg, 0.5 mg = 500 mcg, and 1 mg = 1,000 mcg.

Vial labels are usually printed in mg, while small measured amounts are often easier to talk about in mcg, which is why this calculator works in both. It defaults to mg — the unit most people in the US think in — and the mg/mcg toggle in Step 3 converts the number you typed automatically, so switching units never changes the amount, only how it is written.

Worked Examples

Three common vial sizes, calculated step by step using the same formulas as the tool above.

Example 1 — 10 mg vial, 2 mL of water

Concentration: 10 ÷ 2 = 5 mg/mL. Amount per unit: 5 mg/mL ÷ 100 = 0.05 mg = 50 mcg per unit. To measure 0.25 mg (250 mcg): 250 ÷ 50 = 5 units, which is 0.05 mL. Measurements per vial: 10,000 ÷ 250 = 40.

Example 2 — 5 mg vial, 1 mL of water

Concentration: 5 ÷ 1 = 5 mg/mL. Amount per unit: 50 mcg per unit — the same as Example 1, reached a different way. To measure 500 mcg: 500 ÷ 50 = 10 units, which is 0.10 mL. Measurements per vial: 5,000 ÷ 500 = 10.

Example 3 — 2 mg vial, 2 mL of water

Concentration: 2 ÷ 2 = 1 mg/mL. Amount per unit: 1 mg/mL ÷ 100 = 0.01 mg = 10 mcg per unit. To measure 100 mcg: 100 ÷ 10 = 10 units, which is 0.10 mL. Measurements per vial: 2,000 ÷ 100 = 20.

Reconstitution Math — Frequently Asked Questions

What does concentration mean in reconstitution math?
Concentration is the amount in the vial divided by the water volume you added. A 10 mg vial mixed with 2 mL of water has a concentration of 5 mg per mL (10 ÷ 2 = 5). Every measurement from that vial is based on that concentration.
How many syringe units are in 1 mL?
On a standard U-100 syringe, 100 units equals 1 mL, so 1 unit equals 0.01 mL. That is why the math on this page converts millilitres to syringe units by multiplying by 100.
What is the difference between mg and mcg?
Both measure mass. 1 milligram (mg) equals 1,000 micrograms (mcg). The same amount can be written either way: 0.25 mg and 250 mcg are identical. This calculator defaults to mg and its mg/mcg toggle converts the number you typed automatically.
Why does adding more water change the number of units?
The total amount in the vial never changes — only how spread out it is. More water means a lower concentration, so each syringe unit holds less and you draw more units to measure the same amount. Less water does the opposite.
How do I calculate measurements per vial?
Divide the total amount in the vial by the amount in one measurement, using the same unit for both. A 10 mg vial holds 10,000 mcg; at 250 mcg per measurement, that is 10,000 ÷ 250 = 40 measurements per vial.
Does this calculator recommend an amount to use?
No. This calculator performs vial math only — it converts between concentration, volume, and syringe units for numbers you enter. It does not recommend any amount, schedule, or protocol.

Research Guides

Step-by-step references and concentration charts from the TC Health blog.

How to Reconstitute Peptides (step-by-step) → Retatrutide Reconstitution Chart → BPC-157 + TB-500 Stack Protocol → NAD+ Delivery Methods Compared → MOTS-c Research Guide → Shop TC Health