Peptide Reconstitution Calculator
Peptide Type
Required for optimization — sets the target per-injection dose.
How peptide reconstitution calculations work
Reconstitution is the step where lyophilised (freeze-dried) peptide powder is dissolved in a liquid, usually bacteriostatic water. The calculator on this page does not decide anything for you — it performs arithmetic on the values you enter: the peptide amount printed on the vial, the volume of liquid you add, and the target research amount you want to measure out.
Concentration (mg/mL) = peptide amount (mg) ÷ liquid volume (mL)
Volume (mL) = target amount ÷ concentration
U-100 syringe units = volume (mL) × 100
mcg = mg × 1,000
Worked example: a 10 mg vial reconstituted with 2 mL of bacteriostatic water gives 10 ÷ 2 = 5 mg/mL. A 0.5 mg target amount is 0.5 ÷ 5 = 0.1 mL, which reads as 10 units on a U-100 syringe.
mg, mcg, mL and syringe units
- mg and mcg are masses — how much peptide there is. They never change when you add more water.
- mL is a volume — how much liquid you draw into the syringe.
- Units are marks printed on an insulin syringe. On the common U-100 scale, 100 units = 1 mL, so units are just a re-labelled volume, not a dose.
- Adding more bacteriostatic water lowers the concentration and increases the volume drawn for the same amount of peptide, which usually makes small amounts easier to read.
Why two calculators can disagree
Different results almost always come from different inputs or assumptions rather than different maths. The usual causes are a U-40 syringe scale instead of U-100, a target entered in mg on one tool and mcg on another, vial overfill being counted or ignored, and different rounding of the final syringe reading.
Verify the numbers printed on your own vial and syringe before relying on any calculated figure. PepCalcs reports arithmetic, not guidance — see the methodology page for every formula used.
Frequently asked questions
How does a peptide reconstitution calculator work?
It divides the peptide amount in the vial by the volume of liquid you add to get a concentration, then divides your target amount by that concentration to get an injection volume in mL. Multiplying that volume by 100 gives the mark on a U-100 syringe.
How do you convert mg to mcg?
Multiply milligrams by 1,000. 1 mg equals 1,000 mcg, so 0.25 mg is 250 mcg. To go the other way, divide micrograms by 1,000.
How do you convert mL to units on a U-100 syringe?
A U-100 syringe is graduated so that 100 units equal 1 mL. Units = mL x 100. So 0.25 mL reads as 25 units and 0.05 mL reads as 5 units.
Does adding more bacteriostatic water change the total peptide amount?
No. The vial still contains the same mass of peptide. More liquid lowers the concentration, so the same target amount is drawn as a larger volume — which can be easier to measure accurately on a syringe.
Why do different peptide calculators sometimes show different syringe units?
Usually because of a different assumed syringe scale (U-100 versus U-40), a different rounding step, or a mg/mcg mix-up in the entered values. Check the syringe printed scale and the units on every field before comparing results.
What does peptide concentration mean?
Concentration is the amount of peptide per unit of liquid, normally written mg/mL or mcg/mL. It is the bridge between the amount you want and the volume you draw.
Peptide-specific calculators
Reference guides
- How to Use a Peptide Reconstitution Calculator
- How Peptide Reconstitution Calculations Work
- mg vs mcg: Converting Peptide Amounts
- mL to Units on a U-100 Syringe
- Calculating Peptide Concentration
- Calculating How Much Bacteriostatic Water to Add
Or browse the peptide library for reference profiles of individual compounds.