Peptide calculator
Work out the concentration after reconstitution, the volume to draw for a given amount, and how many samples a vial holds. Arithmetic only — this is not dosing advice.
Milligrams in the vial divided by the millilitres of solvent you added. That is what one millilitre of the solution contains.
The amount you want in one sample divided by the concentration. A U-100 syringe reads 100 units to the millilitre.
The whole vial in micrograms divided by the amount per sample, rounded down to whole samples.
The peptide calculator above turns three numbers into a usable result: the milligrams of peptide in the vial, the millilitres of bacteriostatic water you add, and the amount you want in one sample. From these it calculates the concentration of the solution, the volume to draw and the matching mark on a U-100 syringe. The tool does arithmetic only. It gives no dosing advice, and all compounds in this shop are sold for laboratory research use only.
How the peptide calculator works
Reconstitution is a unit conversion. A lyophilised peptide is a dry powder with a known mass, printed on the label in milligrams (mg). When you add a solvent, that mass is spread evenly through the liquid. The peptide calculator works through three steps:
Concentration: mg in the vial ÷ mL of solvent = mg per mL.
Volume per sample: amount per sample in micrograms (mcg) ÷ (concentration × 1,000) = mL to draw.
Syringe units: mL × 100 = units on a U-100 syringe.
The calculator also divides the whole vial by the amount per sample, so you see how many full samples one vial gives. If the volume is larger than the selected syringe holds, it shows a warning. You can then choose a bigger syringe or use more solvent.
Units in the peptide calculator: mg, mcg and mL
Most errors in reconstitution are unit errors, not arithmetic errors. Peptide vials are labelled in milligrams, but sample amounts in research protocols are often given in micrograms. One milligram is 1,000 micrograms, so a 10 mg vial contains 10,000 mcg. The symbol µg means the same as mcg.
The solvent is measured in millilitres. The amount of solvent does not change how much peptide is in the vial. It only changes how concentrated the solution is. More water gives a weaker solution and a larger volume per sample, which is easier to measure accurately on a small syringe.
Reading a U-100 syringe with the peptide calculator
A U-100 syringe is marked in units, and 100 units equal 1 mL. One unit is therefore 0.01 mL. Common sizes are 1 mL (100 units), 0.5 mL (50 units) and 0.3 mL (30 units). The smaller sizes have finer markings, so they are easier to read for small volumes. The peptide calculator converts the volume into units for the syringe size you select, so the result matches the marks on the barrel.
Peptide calculator example: 10 mg vial with 2 mL of water
A worked example shows each step of the calculation. Assume a 10 mg vial, 2 mL of bacteriostatic water and a sample amount of 500 mcg:
Concentration: 10 mg ÷ 2 mL = 5 mg/mL, which is 5,000 mcg per mL.
Volume per sample: 500 mcg ÷ 5,000 mcg/mL = 0.1 mL.
Syringe units: 0.1 mL × 100 = 10 units on a U-100 syringe.
Samples per vial: 10,000 mcg ÷ 500 mcg = 20 samples.
If you add 3 mL instead of 2 mL, the concentration drops to 3.33 mg/mL and the same 500 mcg needs 15 units. The amount of peptide per sample is the same. Only the volume changes.
Peptide concentration table by vial size
The table shows the concentration for common vial sizes and solvent volumes, plus how many micrograms one unit on a U-100 syringe contains. Values are rounded. For other combinations, use the peptide calculator above.
| Vial | Solvent | Concentration | mcg per syringe unit |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 50 mcg |
| 5 mg | 2 mL | 2.5 mg/mL | 25 mcg |
| 5 mg | 3 mL | 1.67 mg/mL | 16.7 mcg |
| 10 mg | 1 mL | 10 mg/mL | 100 mcg |
| 10 mg | 2 mL | 5 mg/mL | 50 mcg |
| 10 mg | 3 mL | 3.33 mg/mL | 33.3 mcg |
| 15 mg | 2 mL | 7.5 mg/mL | 75 mcg |
| 15 mg | 3 mL | 5 mg/mL | 50 mcg |
| 30 mg | 3 mL | 10 mg/mL | 100 mcg |
Choosing the solvent volume for reconstitution
There is no single correct volume. Most researchers use 1 to 3 mL of bacteriostatic water per vial. Pick a volume that makes the sample volume easy to measure: very small volumes, for example under 5 units, are hard to read accurately. Our guide How much bacteriostatic water per vial? explains the choice in more detail. Bacteriostatic water in 10 mL vials is available in our lab supplies.
Add the solvent slowly along the inside of the glass and let the powder dissolve without shaking. Keep the solution at 2 to 8 °C. A reconstituted peptide is less stable than the dry powder, so reconstitute only what you need. The FAQ covers storage and handling.
Peptide calculator presets for our vials
The compound list in the peptide calculator fills in the vial size of each product in our range, for example Retatrutide in 5, 10 and 15 mg. Every value stays editable, so the calculator also works for vials from other sources. For documented batches, the certificate of analysis confirms identity and purity. You can find these products in the lab-tested peptides category.
Questions about the peptide calculator
Is the peptide calculator a dosage calculator?
No. It converts the numbers you enter into a concentration, a volume and syringe units. It does not suggest amounts. All compounds in this shop are for laboratory research use only.
Does the amount of water change how much peptide is in the vial?
No. The vial always contains the mass printed on the label. The water only sets the concentration, and with it the volume you draw per sample.
Can I use the calculator with a 0.5 mL or 0.3 mL syringe?
Yes. All U-100 syringes use the same scale of 100 units per mL. Select the size in the calculator and it warns you if the volume is more than the syringe holds.
Why does the calculator round the number of samples down?
Only full samples count. The rest of the solution is not enough for one more sample at the amount you entered, so the calculator shows whole numbers only.
For laboratory research use only. Not for human or veterinary use. The peptide calculator performs arithmetic only and is not medical or dosing advice.