The other guides cover the pieces. This one follows a single vial all the way from powder to the mark you draw to, without skipping a step. We'll use BPC-157 because it's one of the most common vials people reconstitute at home, but the arithmetic is identical for any peptide.

The dose below (250 mcg) is used purely as a number to run through the maths. It is not a recommendation, and this article does not suggest what you should take or whether you should take anything. Your dose comes from a qualified healthcare professional. Vialog and this guide only do arithmetic.

The setup

Three numbers, and that's all we need:

Conversion 1 — concentration

How much peptide sits in each millilitre after the water goes in:

5 mg ÷ 2 ml = 2.5 mg/ml

Conversion 2 — volume

First get the dose into the same unit as the concentration: 250 mcg is 0.25 mg. Then:

0.25 mg ÷ 2.5 mg/ml = 0.1 ml

Conversion 3 — units

Turn that volume into a mark on a U-100 syringe:

0.1 ml × 100 = 10 units
Draw to 10 units. On a 1 ml U-100 syringe that's one-tenth of the way up the barrel — a clean, unambiguous mark.

Why the water you chose mattered

That "10 units" wasn't a property of the peptide or the dose — it came from the 2 ml of water. Reconstitute the same 5 mg vial differently and the same 250 mcg dose lands somewhere else entirely:

Same 5 mg vial, same 250 mcg dose:

  • 1 ml water → 5 mg/ml → 5 units
  • 2 ml water → 2.5 mg/ml → 10 units
  • 3 ml water → 1.67 mg/ml → 15 units
  • 5 ml water → 1 mg/ml → 25 units

More water spreads the same dose across more units, which makes the mark easier to read accurately. That's not just convenience — it's the fix for the next problem.

When the app refuses: the under-one-unit case

Suppose you'd added only 1 ml of water and were working with a much smaller dose — say 40 mcg. Run it through:

5 mg ÷ 1 ml = 5 mg/ml · 0.04 mg ÷ 5 = 0.008 ml · × 100 = 0.8 units

Eight-tenths of one unit. There is no honest way to draw that on a U-100 syringe, and rounding it to "1 unit" quietly changes the dose by 25%. So Vialog does something no other calculator does: it refuses to print a number, tells you why, and tells you the fix — add more water. Put in 5 ml instead and the same 40 mcg reads as a drawable 4 units.

Run your own numbers, not the example.

Put your vial, your water and your dose into Vialog. It follows all three conversions, shows the working, and refuses anything your syringe can't draw.

See Vialog — coming soon

Drawing to the mark

Once you have a unit number, the physical part is simple: pull the plunger to that graduation, tap out the air, and check the mark at eye level. If the number isn't a clean line on your barrel — you calculated 12.5 units on a syringe marked every 2 — that's usually another sign to reconsider the water so your routine doses land on marks you can hit every time.

General educational information about arithmetic and mechanics only — not medical advice, not a dosing recommendation. Vialog is a calculator and a log, not a medical device, and never tells you what to take. Always consult a qualified healthcare professional.

Frequently asked

How many units do I draw for a peptide dose?

Divide your dose by the concentration for the volume in ml, then multiply by 100 for units on a U-100 syringe. The concentration comes from the mg in the vial divided by the ml of water you added.

How do you reconstitute a 5 mg BPC-157 vial?

Add bacteriostatic water — the amount is your choice and sets the concentration. 5 mg in 2 ml is 2.5 mg/ml. From there, dose ÷ concentration × 100 gives units. See the full step-by-step.

What if my calculated dose is less than one unit?

Don't round it. Add more water so the same dose reads as a larger, drawable number of units, then recalculate.

Start from the beginning: How to reconstitute a peptide, step by step.