Concentration
How much compound is in each milliliter after mixing.
mg in vial ÷ mL of liquid = mg/mL10 mg mixed with 2 mL = 5 mg/mL.
PEPTIDE MATH
This calculator teaches concentration relationships. It does not recommend a dose or tell you what to inject.
On a U-100 syringe, 100 units is 1 mL. “Units” describe volume—not the mass of the compound.
Milligrams describe mass; milliliters describe volume. 1 mg is 1,000 mcg. International units (IU) describe substance-specific biological activity and are not the same as U-100 syringe markings.
THE CORE MATH
How much compound is in each milliliter after mixing.
mg in vial ÷ mL of liquid = mg/mL10 mg mixed with 2 mL = 5 mg/mL.
How much volume holds a given amount on a U-100 syringe.
(amount ÷ mg/mL) × 100 = unitsAt 5 mg/mL, 0.5 mg is (0.5 ÷ 5) × 100 = 10 units.
How many equal portions a vial holds on paper.
mg in vial ÷ amount per portionA 10 mg vial holds 20 portions of 0.5 mg. Storage limits may run out before the vial does (see below).
Unit check: 1 mg = 1,000 mcg. A mix-up between mg and mcg is a 1,000× error, the most serious math mistake there is.
WORKED EXAMPLES
These rows are arithmetic only. They show how concentration changes the volume, not how much of anything to use.
| Vial + liquid | Concentration | 10 units holds | 1 mg takes up |
|---|---|---|---|
| 5 mg + 2 mL | 2.5 mg/mL | 0.25 mg | 40 units |
| 10 mg + 2 mL | 5 mg/mL | 0.5 mg | 20 units |
| 10 mg + 1 mL | 10 mg/mL | 1 mg | 10 units |
| 20 mg + 2 mL | 10 mg/mL | 1 mg | 10 units |
| 20 mg + 4 mL | 5 mg/mL | 0.5 mg | 20 units |
| 30 mg + 3 mL | 10 mg/mL | 1 mg | 10 units |
| 50 mg + 5 mL | 10 mg/mL | 1 mg | 10 units |
| 100 mg + 5 mL | 20 mg/mL | 2 mg | 5 units |
| 500 mg + 5 mL | 100 mg/mL | 10 mg | 1 unit |
20 mg in 2 mL, 30 mg in 3 mL, and 50 mg in 5 mL are all 10 mg/mL. The unit math is the same for all three. A bigger vial just holds more portions.
Adding more liquid doesn’t change how much compound is in the vial. It spreads it out, so each amount takes up more units. That can make very small amounts easier to measure.
If a vial has a different fill (15 mg instead of 10 mg) or was mixed with a different volume, every row changes. Recalculate from the actual label.
READING THE SYRINGE
A U-100 insulin-style syringe is marked so that 100 units = 1 mL, and 1 unit = 0.01 mL. The markings measure liquid. How much compound is in that liquid depends on the concentration.
Anything over 100 units is more than 1 mL.
Volumes under about 5 units are difficult to read precisely. Example: 20 mg in 2 mL puts 0.25 mg in 2.5 units. The same vial mixed with 4 mL puts 0.25 mg in 5 units.
“Units” on a syringe are volume markings. “IU” (international units) on a label measure biological activity and are specific to each substance. They are not interchangeable.
BLEND MATH
In a pre-mixed blend, every draw contains all the ingredients in a fixed (“locked”) ratio. You can’t change one without changing all of them.
Add up every ingredient, then divide by the liquid volume.
total mg ÷ mL = total mg/mLEach ingredient’s share of a draw equals its share of the vial.
amount in draw × (ingredient mg ÷ total mg)A 70 mg blend listed as GHK-Cu 50 mg + BPC-157 10 mg + TB-500 10 mg, mixed with 3 mL = 23.33 mg/mL. 10 units (0.1 mL) holds about 2.33 mg total: GHK-Cu ~1.67 mg, BPC-157 ~0.33 mg, TB-500 ~0.33 mg.
BLEND CALCULATOR
Enter the amount of each ingredient from the label (leave unused rows at 0), the liquid volume, and a volume in units.
If two products share an ingredient, such as a blend that already contains BPC-157 alongside a separate BPC-157 vial, the amounts add together. Count the total of each compound, not each vial.
If a label gives only a blend name and a total (such as “70 mg”), you can’t work out how much of each ingredient is present. Ask for a per-ingredient breakdown and a COA.
IU, MCG & LIQUID VIALS
Divide total IU by liquid volume. Example: 10,000 IU mixed with 10 mL = 1,000 IU/mL, so 10 units (0.1 mL) holds 100 IU. There is no single IU-to-mg conversion; each substance has its own.
Some products, like vitamin B12, arrive already in solution. Nothing is added. Read the printed concentration: 1,000 mcg/mL and 5,000 mcg/mL lots differ by 5×, so the same volume holds 5× more.
MIXING & STORAGE
Most research peptides ship as a freeze-dried (lyophilized) powder and are mixed with liquid before use. These are general handling points. Always follow the specific product label.
Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that allows a vial to be entered more than once. Sterile water has no preservative and is meant for single use.
Add the liquid slowly down the inside wall of the vial and swirl gently until dissolved. Shaking and foaming can damage some peptides, and some (such as AOD-9604) can gel if shaken or mixed cold.
Mixed vials are typically refrigerated at 2–8 °C (36–46 °F) and kept away from light. NAD+ and copper peptides are especially light-sensitive. Don’t freeze a mixed vial unless the label says to.
Many references use about 28 days as the limit for a mixed, multi-use vial, and some products (like glutathione) are shorter. A vial can hold more portions “on paper” than can be used within that window.
Most mixed peptides are clear and colorless. Copper peptides are normally blue (GHK-Cu) or blue-green (AHK-Cu), and NAD+ can be pale yellow. Cloudiness, particles, or an unexpected color are reasons to discard.
Different products shouldn’t be mixed in the same syringe unless they were made as a blend. NAD+ and glutathione in particular are kept separate from peptides.
CHECK YOUR WORK
A 1,000× difference. Write the unit next to every number.
Syringe units measure volume. IU measure activity. They aren’t interchangeable.
A chart built for 10 mg in 2 mL is wrong for 10 mg in 3 mL. Recalculate for every vial.
“1 mg of blend” is not 1 mg of each ingredient. Split it by each ingredient’s share.
Liquid vials come in different strengths. Read the printed mcg/mL every time.
Rounding 2.5 units to 3 is a 20% change. Use a smaller syringe or a larger mixing volume.
Pep Guide explains the math so labels and research papers make sense. It is not dosing guidance. Doses belong on an FDA label or in a published human trial, and they should be set with a licensed clinician.