Reconstitution calculator
Enter what's in the vial, how much bacteriostatic water you're adding, and the amount you need to measure per draw. You get the concentration, the exact U-100 syringe reading, and how many full draws the vial covers, updating live as you type.
The number on the vial label (e.g. 10 mg) — the powder, before any water.
How much BAC water you mix into the vial. More water = more diluted — same total peptide.
The amount of peptide you want each time — not the amount of liquid. We handle the liquid part. We never suggest an amount; enter the figure your research calls for.
U-100 insulin syringe · 100 units = 1 mL · numbered every 10 units
Fill in all three fields and the syringe reading appears here, live.
Concentration
—
mg/mL
Per unit
—
mcg/unit
Draws per vial
—
full draws
This calculator is a reference for working with research materials sold for laboratory use only. It performs arithmetic on the numbers you enter; it does not recommend amounts, protocols, or products, and nothing on this page is medical advice. See our methodology.
How reconstitution math works
Research peptides ship as lyophilized (freeze-dried) powder. Before anything can be measured out, the powder is dissolved in bacteriostatic water. Only three numbers matter from that point on, and the whole calculation is division:
- Concentration is the peptide amount divided by the water volume: mg ÷ mL = mg/mL.
- Micrograms per unit converts that to U-100 syringe terms. One mL is 100 units, so mcg per unit = (mg × 1,000) ÷ (mL × 100).
- Units to draw is your amount divided by the strength of each unit: draw amount in mcg ÷ mcg per unit.
Worked example
Say a vial holds 10 mg and you add 2 mL of bacteriostatic water, and the amount your own protocol calls for is 500 mcg per draw (that number is yours; we never supply it):
- Concentration: 10 ÷ 2 = 5 mg/mL
- Per unit: (10 × 1,000) ÷ (2 × 100) = 50 mcg per unit
- Units to draw: 500 ÷ 50 = 10 units
- Draws per vial: 10,000 mcg ÷ 500 mcg = 20 full draws
The key intuition: water volume changes only how spread out the peptide is. Add 4 mL instead of 2 and the same 500 mcg becomes a 20-unit draw instead of 10. Nothing about the material changed, just how much liquid carries it.
Frequently asked questions
How much bacteriostatic water should I add?
There is no single right amount. The water volume only sets the concentration, not how much peptide is in the vial. More water means each draw is a larger, easier-to-read volume on the syringe; less water means smaller draws. A practical approach is to pick a volume that lands your draws in a comfortable range on a U-100 syringe, roughly 5 to 50 units, and the calculator shows exactly where any combination lands.
Does adding more water change the dose?
No. The vial holds the same total amount of peptide regardless of how much water you add. More water spreads that amount across more liquid, so you draw a larger volume to measure the same mass. Concentration changes; the amount you measure does not.
What is the difference between U-100 units and mL?
A U-100 insulin syringe divides 1 mL into 100 units, so 1 unit equals 0.01 mL. Units are simply a finer scale for reading small volumes. To convert, divide units by 100 to get mL.
Can I use sterile water instead of bacteriostatic water?
Sterile water contains no preservative, so it suits single-use reconstitution only. Bacteriostatic water contains 0.9% benzyl alcohol, which suppresses bacterial growth between draws, and that is why it is the standard choice for multi-draw research vials.
How long does a reconstituted vial stay usable?
It varies by compound. As a general rule of lab practice, vials reconstituted with bacteriostatic water are kept refrigerated at 2 to 8°C and used within several weeks, while unreconstituted lyophilized powder is far more stable. Check published stability data for the specific peptide you are working with rather than relying on a blanket number.
Paying too much per vial?
We keep close tabs on vendor pricing and rank every tracked lab by effective price-per-milligram, discount codes included.