Peptide Reconstitution Calculator — Dose, Volume & Syringe Units
Enter the peptide amount in your vial, the volume of BAC water you plan to add, and your target dose. The peptide reconstitution calculator instantly returns the reconstituted concentration, the exact injection volume, the number of syringe units to draw on a U-100 insulin syringe, and the number of doses remaining in the vial — with the formula shown at every step.
This free tool is part of the Peptide Calculator Tools suite. For a general-purpose calculator that also covers mixing, dilution and syringe conversion, see our main Peptide Calculator.
Free Peptide Reconstitution Calculator
Enter your vial amount, BAC water volume, target dose and syringe size. The result card updates in real time and always shows the formula.
What Is a Peptide Reconstitution Calculator?
A peptide reconstitution calculator is a free online tool that performs the math clinicians, pharmacists, researchers and self-directed learners need to dissolve a lyophilized (freeze-dried) peptide in a measured volume of diluent and then dose that solution accurately. Reconstitution has three unknowns that must agree with each other: the peptide mass in the vial, the diluent volume you add, and the dose you intend to draw. The calculator uses three relationships to resolve all three:
Because every insulin syringe uses the same U-100 scale — 100 units equals 1 mL — the third formula works unchanged for a 30-unit, 50-unit or 100-unit syringe. Only the barrel length changes; the math never does. The peptide reconstitution calculator on this page exposes all three formulas on screen so you can verify the result yourself rather than trusting a black box.
How to Use This Calculator
Five steps. The result updates as you type.
- Enter the peptide amount. Type the total mg of lyophilized peptide printed on the vial or in the certificate of analysis. Common vial sizes are 2 mg, 5 mg, 10 mg, 15 mg, 20 mg, 30 mg and 50 mg. The default unit is mg; switch to mcg if your vial label uses micrograms.
- Enter the diluent volume. Type the mL of bacteriostatic water (BAC) or other diluent you plan to add. Common volumes are 1 mL, 2 mL and 3 mL. For a low target dose, add more water to make the solution easier to measure on a small syringe.
- Enter the desired dose. Type your target dose in mg or mcg using the unit selector. Sub-milligram doses are almost always expressed in mcg (1 mg = 1,000 mcg).
- Select the syringe. Pick the 30-unit, 50-unit or 100-unit insulin syringe you plan to use. All three use the U-100 scale; smaller barrels spread the same volume over fewer ticks so dose lines are easier to read.
- Read the result. The result card shows concentration, injection volume, syringe units, total reconstituted volume, number of doses in the vial, peptide remaining after this dose and the dose as a fraction of the vial.
How to Calculate Peptide Concentration
Concentration describes how much peptide mass is dissolved per milliliter of solution. It is the single most important number in reconstitution, because every downstream calculation (injection volume, syringe units, doses per vial) derives from it.
To convert to mcg/mL, multiply by 1,000:
Mathematical Example. Reconstituting a 10 mg peptide in 2 mL BAC water: 10 ÷ 2 = 5 mg/mL, which equals 5,000 mcg/mL. The same 10 mg peptide in 3 mL BAC water yields 3.33 mg/mL, which is 3,333 mcg/mL. The same peptide in 1 mL BAC water yields 10 mg/mL, which is 10,000 mcg/mL.
For a dedicated concentration-only tool, see our Peptide Concentration Calculator.
How to Calculate Injection Volume
Once you know the concentration, the injection volume is the target dose divided by that concentration:
Equivalently, in mcg units:
Mathematical Example. At 5 mg/mL concentration, a 250 mcg dose = 0.25 mg ÷ 5 mg/mL = 0.05 mL. The same 250 mcg dose at 3.33 mg/mL requires 0.075 mL. The same dose at 10 mg/mL requires only 0.025 mL — easier to under-dose because the volume is so small.
The injection volume cannot exceed the total reconstituted volume. The calculator returns an accessible error if you ask for more solution than the vial contains.
How to Calculate Syringe Units
Every standard insulin syringe uses the U-100 scale, meaning 100 units = 1 mL. To convert injection volume to syringe units:
Each unit equals 0.01 mL, regardless of whether the syringe holds 30 units (0.3 mL), 50 units (0.5 mL) or 100 units (1 mL). A 5-unit dose occupies the same volume on all three syringes; only the visual spacing differs.
Mathematical Example. 0.05 mL × 100 = 5 units. 0.15 mL × 100 = 15 units. 0.50 mL × 100 = 50 units (a full 0.5 mL syringe). 1.00 mL × 100 = 100 units (a full 1 mL syringe).
For the inverse — converting units on a syringe back to volume — see our Peptide Syringe Calculator.
How Many Doses Are in a Peptide Vial?
The number of doses in a vial equals total peptide mass divided by per-dose mass:
Mathematical Example. A 10 mg vial at 250 mcg per dose contains 10 ÷ 0.25 = 40 doses. The same vial at 500 mcg per dose contains 20 doses. A 5 mg vial at 100 mcg per dose contains 50 doses.
Always compare the dose count to the peptide's stability window after reconstitution — typically 28 to 56 days refrigerated for BAC-water solutions. If your dose count would outlast the stability window, reconstitute with less BAC water so you discard fewer doses when the vial expires.
For general dose math without reconstitution, see our Peptide Dosage Calculator.
How Much BAC Water Should Be Used?
There is no single correct BAC water volume. The decision is a trade-off between ease of measurement (more water = larger volume per dose = more syringe units = easier to read) and concentration per mL (less water = more concentrated = smaller volume per dose = less easy to read). A common rule of thumb: pick the BAC water volume that places your target dose between 5 and 50 units on a 100-unit insulin syringe.
| Vial size | If target dose ≥ 500 mcg | If target dose < 500 mcg |
|---|---|---|
| 2 mg | 2 mL BAC → 1 mg/mL | 3 mL BAC → 0.667 mg/mL |
| 5 mg | 2 mL BAC → 2.5 mg/mL | 3 mL BAC → 1.667 mg/mL |
| 10 mg | 2 mL BAC → 5 mg/mL | 3 mL BAC → 3.333 mg/mL |
| 15 mg | 3 mL BAC → 5 mg/mL | 5 mL BAC → 3 mg/mL |
| 20 mg | 3 mL BAC → 6.667 mg/mL | 5 mL BAC → 4 mg/mL |
| 30 mg | 3 mL BAC → 10 mg/mL | 5 mL BAC → 6 mg/mL |
| 50 mg | 5 mL BAC → 10 mg/mL | Use a 0.5 mL syringe |
For a dedicated BAC water tool, see our Peptide BAC Water Calculator.
Peptide Reconstitution Examples
All examples below are mathematical demonstrations of the formulas above. They are not medical recommendations.
Example Calculation — 10 mg vial, 2 mL BAC, 250 mcg dose
Number of doses = 10 ÷ 0.25 = 40 doses. Peptide remaining after this dose = 9.75 mg.
Example Calculation — 5 mg vial, 3 mL BAC, 250 mcg dose
Number of doses = 5 ÷ 0.25 = 20 doses. Peptide remaining = 4.75 mg.
Example Calculation — 15 mg vial, 3 mL BAC, 250 mcg dose
Number of doses = 15 ÷ 0.25 = 60 doses. Peptide remaining = 14.75 mg.
Example Calculation — 30 mg vial, 3 mL BAC, 2.5 mg dose
Number of doses = 30 ÷ 2.5 = 12 doses. Peptide remaining = 27.5 mg.
Example Calculation — 50 mg vial, 5 mL BAC, 2 mg dose
Number of doses = 50 ÷ 2 = 25 doses. Peptide remaining = 48 mg.
Quick-reference — 10 mg vial reconstituted with 2 mL BAC (5 mg/mL)
| Target dose | Volume | Units on 100-unit syringe | Units on 50-unit syringe | Units on 30-unit syringe |
|---|---|---|---|---|
| 100 mcg (0.1 mg) | 0.02 mL | 2 units | 2 units | 2 units |
| 250 mcg (0.25 mg) | 0.05 mL | 5 units | 5 units | 5 units |
| 500 mcg (0.5 mg) | 0.10 mL | 10 units | 10 units | 10 units |
| 1 mg | 0.20 mL | 20 units | 20 units | 20 units |
| 2 mg | 0.40 mL | 40 units | 40 units | — (over capacity) |
| 2.5 mg | 0.50 mL | 50 units | 50 units (full) | — |
| 5 mg | 1.00 mL | 100 units (full) | — | — |
Common Reconstitution Calculation Mistakes
Peptide Reconstitution FAQs
What is a peptide reconstitution calculator?
A peptide reconstitution calculator is a free online tool that performs the math needed to dissolve a lyophilized peptide in a measured diluent and then dose that solution. It returns concentration per mL, injection volume, syringe units, the number of doses in the vial, and the peptide remaining after each dose — with the formula shown.
How do you use a peptide reconstitution calculator?
Enter the peptide mass in mg, the BAC water volume in mL, your target dose in mg or mcg, and the syringe size. The calculator instantly returns the reconstituted concentration, the injection volume, the syringe units and the number of doses. Try our full Peptide Calculator for additional controls.
How much BAC water should I add to a peptide?
Common BAC water volumes are 1 mL, 2 mL and 3 mL. Add more water for an easier-to-measure concentration with a low-volume syringe, or less water for higher concentration per mL. The choice depends on your target dose. For a dedicated tool, see our Peptide BAC Water Calculator.
How much BAC water is needed for a 10 mg peptide?
For a 10 mg peptide, 2 mL BAC water yields 5 mg/mL (5,000 mcg/mL) — a comfortable middle concentration for 1 mL insulin syringes. 3 mL yields 3.33 mg/mL for an even easier-to-measure solution when your target dose is below 500 mcg. 1 mL yields 10 mg/mL when your dose is at the upper end of the range.
How do I calculate peptide concentration?
Concentration in mg/mL equals peptide mass in mg divided by diluent volume in mL. For example, 10 mg peptide in 2 mL BAC water equals 5 mg/mL, which is also 5,000 mcg/mL. For a dedicated tool, see our Peptide Concentration Calculator.
How do I calculate peptide injection volume?
Injection volume in mL equals target dose in mg divided by concentration in mg/mL. For example, 0.25 mg ÷ 5 mg/mL equals 0.05 mL, which is 5 units on a U-100 syringe.
How many doses are in a reconstituted peptide vial?
Number of doses equals total vial mg divided by per-dose mg. A 10 mg vial at 250 mcg per dose contains 40 doses. A 5 mg vial at 500 mcg per dose contains 10 doses. Always compare the dose count to the peptide's stability window after reconstitution.
Can I use a peptide reconstitution calculator online?
Yes. The Peptide Calculator Tools reconstitution calculator runs entirely in your browser, is free to use, requires no account and works on every device.
What is the difference between reconstitution and dilution?
Reconstitution dissolves a lyophilized peptide powder in a measured diluent to produce the stock solution. Dilution further reduces the concentration of an already-reconstituted solution by adding more diluent. Both follow the same math: concentration equals mass divided by volume. For dilution, see our Peptide Dilution Calculator.
How accurate is a peptide reconstitution calculator?
The math is exact to the precision of your inputs. Real-world accuracy depends on the precision of your syringe, complete dissolution of the peptide and accurate measurement of the diluent volume. The calculator always shows the formula so you can verify the result yourself.
Medical Disclaimer
The Peptide Calculator Tools reconstitution calculator and the educational content on this page are provided for informational and educational purposes only. They are not medical advice and do not constitute a doctor-patient relationship. The calculator performs mathematical conversions based on user-provided values; it does not recommend, prescribe or validate any particular dose for any particular person. Peptide products sold for research use are not approved by the U.S. Food and Drug Administration for human use outside a clinical setting. Compounded peptides should be used only under the supervision of a licensed clinician. Always verify your reconstituted concentration against the manufacturer's certificate of analysis and follow the dosing protocol prescribed by your healthcare provider.