Peptide Reconstitution Calculator
Calculate the concentration of a reconstituted vial and the syringe units for a given amount.
For research purposes only. Not intended for human consumption.
DRAW SYRINGE TO
units (0.05 ml)
How to use the peptide calculator
- Pick your syringe. Insulin syringes are graduated in units, not millilitres. A U-100 1 ml syringe holds 100 units, so one unit equals 0.01 ml.
- Enter the peptide amount. This is the total mass of lyophilised powder in the vial, printed on the label — for example 5 mg or 10 mg.
- Enter the bacteriostatic water volume. The volume you reconstitute with sets the concentration. Less water gives a higher concentration and a smaller draw; more water gives a lower concentration and a larger, easier-to-measure draw.
- Enter the target amount. The calculator converts it into syringe units and shows the concentration in mg/ml plus how many aliquots of that size the vial contains.
The reconstitution formula
Every reconstitution calculation reduces to two steps. First the concentration, then the volume:
concentration (mg/ml) = peptide amount (mg) ÷ bacteriostatic water (ml)volume to draw (ml) = target amount (mg) ÷ concentration (mg/ml)syringe units = volume to draw (ml) × 100
Worked example: a 5 mg vial reconstituted with 2 ml of bacteriostatic water gives 2.5 mg/ml. A target amount of 250 mcg (0.25 mg) is 0.25 ÷ 2.5 = 0.1 ml, which is 10 units on a U-100 insulin syringe.
Handling and storage notes
Add the bacteriostatic water slowly down the inside wall of the vial rather than directly onto the powder, and swirl gently instead of shaking — peptides are fragile and vigorous agitation can degrade them. Store lyophilised vials at room temperature away from light; refrigerate reconstituted solutions at 2–8°C and use them within about 30 days. Refer to the batch Certificate of Analysis for compound-specific stability data.
This calculator is provided as a laboratory reference tool. All products and calculations are for in-vitro research use only and are not intended for human or animal consumption.
Browse our research peptide catalog, or read the FAQ for storage, purity and Certificate of Analysis details.
Reconstitution FAQ
What is bacteriostatic water?
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, which prevents bacterial growth. It allows reconstituted peptides to be stored for up to 30 days at 2–8°C without contamination.
How much bacteriostatic water should I add?
This depends on the peptide and the measurement accuracy you need. Common amounts are 1–3 ml for a 5–10mg vial. More water = lower concentration = a larger, easier-to-measure draw.
Why are insulin syringe units important?
Insulin syringes are calibrated in "units." On a standard 1ml syringe (U-100), 100 units = 1 ml, so 1 unit = 0.01 ml. This makes drawing very small volumes much more accurate.
How long is a reconstituted vial stable?
Most reconstituted peptides are stable for 28–30 days when stored at 2–8°C. Always refer to the COA and stability data for your specific peptide.
Can I freeze the reconstituted solution?
Generally not recommended. Freeze/thaw cycles can damage the peptide structure. Store unreconstituted lyophilized vials at room temperature, and reconstituted solutions in the refrigerator only.