Plain-words guide
How mixing works: mg, mL and units explained
If the words on a peptide vial and a syringe confuse you, this page is for you. No chemistry. Just what the numbers mean and how they fit together.
The vial is a powder with a number on it
Most peptide vials hold a dry powder. The label gives a weight in milligrams, written "mg." That weight is everything in the vial. It is not one use. A "5 mg vial" means 5 mg of peptide total, sitting at the bottom as a powder.
mg means milligram. It measures weight. One thousand mcg (micrograms) make one mg. So 250 mcg is 0.25 mg, and 1 mg is 1,000 mcg.
Water turns the powder into a liquid you can measure
A powder cannot be measured with a syringe. So water is added to the vial, the powder dissolves, and now the peptide is spread evenly through the liquid. This step is what people call "reconstitution" or "mixing."
The amount of water is measured in milliliters, written "mL." That is a volume, not a weight. This is the part that trips people up: mg is weight, mL is volume, and they are not the same kind of number. A 5 mg vial is not a 5 mL vial.
How much water to add is not something this site tells you. It comes from your product's instructions or a licensed doctor. We only do the math on the amount you used.
Strength: how much peptide is in each mL
Once the powder is dissolved, every milliliter of liquid holds the same share of peptide. The share is the vial weight divided by the water.
5 mg of powder + 2 mL of water = 2.5 mg in every mL.
5 mg of powder + 1 mL of water = 5 mg in every mL. Same vial, less water, stronger liquid.
This number, "mg per mL," is the one that matters for everything that follows. Write it on the vial after you mix so you do not have to remember.
The syringe measures in "units"
Insulin syringes, the small ones most people use for peptides, are marked in units instead of mL. On a standard "U-100" syringe, 100 units is 1 mL. So:
| Mark on the syringe | Liquid inside |
|---|---|
| 5 units | 0.05 mL |
| 10 units | 0.10 mL |
| 50 units | 0.50 mL |
| 100 units | 1.00 mL (a full 1 mL syringe) |
Syringes come in 1 mL (100 units), 0.5 mL (50 units) and 0.3 mL (30 units) sizes. The smaller ones have the same size unit, just fewer of them. "U-100" is printed on the syringe or its packaging; that is the standard this site assumes (ISO 8537).
Putting it together
Say your vial is 5 mg, you added 2 mL of water, and the amount you want in one draw is 250 mcg.
- Turn mcg into mg. 250 mcg is 0.25 mg.
- Find the strength. 5 mg divided by 2 mL is 2.5 mg per mL.
- Find the liquid. 0.25 mg divided by 2.5 mg per mL is 0.1 mL.
- Find the mark. 0.1 mL times 100 is the 10 unit mark.
The calculator does these four steps for you and prints them, so you can check each one.
Mistakes people make with the numbers
- Mixing up mcg and mg. Off by a thousand. If a number looks wildly big or small, check the unit first.
- Mixing up mg and mL. One is weight, the other is volume. The vial label is mg; the water is mL.
- Forgetting how much water went in. The strength depends on it. Write it on the vial.
- Reading the syringe as mL when it is marked in units. Divide units by 100 to get mL.
- Using a syringe that is too small. A 0.3 mL syringe stops at 30 units. If your mark is past that, the calculator will say so.
What this page does not cover, on purpose
It does not say how much water to add, which water to use, how much peptide to take, or how often. Those are not math questions; they depend on you and your product, and they belong with a licensed doctor. Our reasons are spelled out on the How we check page.
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