What is the difference between mg and mcg?

A milligram (mg) is 1,000 micrograms (mcg). So 0.25 mg = 250 mcg. Most peptide vials are labeled in mg (e.g., 5 mg), while doses are often discussed in mcg (e.g., 250 mcg). The calculator handles conversions automatically — just make sure you select the correct unit for each field.

Why do syringe units change when I switch syringe size?

They don't — the unit markings on all U-100 insulin syringes mean the same thing: 1 unit = 0.01 mL. What changes is the total capacity. A 0.3 mL syringe holds up to 30 units, a 0.5 mL up to 50 units, and a 1 mL up to 100 units. If your draw volume exceeds the syringe capacity, the calculator will warn you to choose a larger syringe or increase your concentration.

How are doses per vial calculated?

Doses per vial = total peptide in the vial divided by your dose amount. For example, a 5 mg vial at 250 mcg (0.25 mg) per dose gives 5 / 0.25 = 20 doses. The calculator floors this number because partial doses at the end of a vial are not reliable to measure.

What makes a setup impractical?

A setup is impractical when the draw volume is either too large for the syringe (e.g., needing 0.6 mL on a 0.3 mL syringe) or too small to measure accurately (e.g., under 2 units). The fix is usually to adjust the water volume: less water = higher concentration = smaller draw volumes, and vice versa.

Why does the calculator recommend bacteriostatic water (BAC water)?

Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth. This is important because a reconstituted vial is punctured multiple times over days or weeks. Sterile water is preservative-free and intended for single-use preparations only.

Can I use a different type of syringe?

This calculator is designed for U-100 insulin syringes, which are the most common format for subcutaneous peptide injection in research settings. U-100 means 100 units per mL. If you use a non-insulin syringe that reads in mL directly, use the draw volume in mL from the results.

What if my peptide vial is a different size than the presets?

All fields accept custom values. Click on a preset to quick-fill, or type any number directly into the input field. The calculator works with any positive peptide amount.

Does the number of vials affect the dose calculation?

No — concentration and draw volume are calculated per vial. The vial count is used only to check whether your total available peptide across all vials is sufficient for the requested dose. For most users, 1 vial is the correct setting.

Research Tool

Peptide Reconstitution Calculator

Enter your vial size, diluent volume, and desired dose to instantly calculate the exact draw volume and syringe units. No manual unit conversion needed.

Inputs

Peptide Amount

BAC Water Volume

Desired Dose

Syringe Type

U-100 insulin syringes. 1 unit = 0.01 mL.

5 mg2 mL BAC water250 mcg dose1 mL (U-100)

Results

Concentration

2.50 mg/mL2500 mcg/mL

Draw Volume

0.10 mL

Syringe Units (U-100)

10 units

Doses per Vial

20 doses

Instructions

Step 1: Add 2 mL of bacteriostatic water to the 5 mg vial. Swirl gently until dissolved. Step 2: Using a 1 mL (U-100) insulin syringe, draw to the 10-unit mark (0.10 mL) for a 250 mcg dose.

All inputs are normalized to base units before calculation: peptide mass to mg, dose to mg, volume to mL. If you enter a dose in mcg, the engine divides by 1,000 to convert to mg first.

Concentration = Peptide Amount (mg) / Water Volume (mL)

Draw Volume = Desired Dose (mg) / Concentration (mg/mL)

Syringe Units = Draw Volume (mL) x 100(U-100 standard: 100 units = 1 mL, so 1 unit = 0.01 mL)

Doses per Vial = Total Peptide (mg) / Dose Amount (mg)

This tool is provided for educational and calculation-support purposes only. It is not intended as individualized medical advice. Always consult qualified professionals and follow applicable regulations for your research application.