Peptide Reconstitution Calculator: Water & Syringe Units
Enter the vial amount and a target amount supplied by an authorised source, then choose the U-100 syringe mark you want the arithmetic to reach. PepExact calculates the corresponding volume of bacteriostatic water (BAC water) and the resulting concentration, with every formula shown.
This calculator works backwards from values you provide. It does not choose a target amount, recommend a reconstitution protocol or determine whether a compound is appropriate.
Add
2 mL of water
and each 250 mcg dose lands on 10 units.
Resulting concentration
2.5 mg/mL
2,500 mcg/mL
Doses in this vial
20
Show the math
- 1. Volume you want one dose to be: 10 units ÷ 100 units/mL = 0.1 mL
- 2. Concentration that makes it work: 250 mcg ÷ 0.1 mL = 2,500 mcg/mL (2.5 mg/mL)
- 3. Water to add: 5,000 mcg ÷ 2,500 mcg/mL = 2 mL
- 4. Doses in the vial: 5,000 mcg ÷ 250 mcg = 20 full doses
Other round-number options
| Draw per dose | Water to add |
|---|---|
| 5 units | 1 mL |
| 10 units | 2 mL |
| 20 units | 4 mL |
| 25 units | 5 mL |
| 50 units | 10 mL |
How reverse reconstitution math works
The tool solves for water volume from three inputs: the total amount in the vial, a user-supplied target amount, and the selected U-100 syringe mark. The shared engine uses these steps (identical to the “Show the math” output):
- Volume for one draw:
target units ÷ 100 units/mL - Required concentration:
target amount (mcg) ÷ volume per draw (mL) - Water to add:
vial amount (mcg) ÷ concentration (mcg/mL)
How water volume changes concentration
The volume of water changes the concentration, not the total amount contained in the vial. More water produces a lower concentration and a larger liquid volume for the same user-supplied amount. Less water produces a higher concentration and a smaller liquid volume.
PepExact calculates the arithmetic only. It does not recommend a water volume. Product instructions, physical vial capacity and authorised protocols must be considered separately.
Illustrative reverse-reconstitution calculation
Illustrative arithmetic only—not a recommended amount or protocol.
Using the same default values preloaded in the calculator above (5 mg vial, 250 mcg target amount, 10 U-100 units):
- Volume for one draw = 10 ÷ 100 = 0.1 mL
- Concentration = 250 mcg ÷ 0.1 mL = 2,500 mcg/mL (2.5 mg/mL)
- Water to add = 5,000 mcg ÷ 2,500 mcg/mL = 2 mL
- Corresponding U-100 mark = 10 units (0.1 mL)
Reconstitution calculator questions
How much bacteriostatic water should I add?
That is exactly what this calculator solves for. Enter the vial amount, a target amount supplied by an authorised source, and the U-100 syringe mark you want one draw to reach; it returns the millilitres of bacteriostatic water (BAC water) that produce that result, and shows every step. PepExact does not recommend a water volume — it only does the arithmetic on the numbers you provide, and physical vial capacity and product instructions must be considered separately.
What does a peptide reconstitution calculator calculate?
It calculates concentration and measurement values from the vial amount, water volume and user-supplied target amount. This reverse calculator can instead solve for water volume from a selected U-100 syringe mark.
Why does water volume change the syringe units?
Changing the water volume changes the concentration. A different concentration means the same user-supplied amount occupies a different liquid volume and therefore reaches a different U-100 syringe mark.
Does PepExact recommend how much water to add?
No. PepExact performs arithmetic using the values entered. It does not select a water volume, target amount or protocol.
Why can two reconstitution calculators give different results?
Results can differ when the calculators use different vial amounts, water volumes, mg-to-mcg conversions, syringe scales or rounding rules. Compare every input and intermediate calculation before comparing the final unit number.
What does U-100 mean?
U-100 means the syringe scale represents 100 units per millilitre. On that scale, 1 unit represents 0.01 mL.
Related tools
PepExact is a measurement tool, not medical advice. It calculates volumes and concentrations from numbers you provide — it never suggests a dose.