Peptide Dosage Calculator

Enter your vial size, how much BAC water you added, and your desired dose. This calculator gives you the exact syringe units to draw, plus a visual diagram showing the fill line on your syringe.

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How to Use This Calculator

Step 1: Select a Preset or Enter Custom Values

Click BPC-157, TB-500, or Tirzepatide to auto-fill common vial sizes and starting doses. Or enter your own values manually. The calculator works with any peptide.

Step 2: Enter Your Vial Information

• Peptide in Vial — The total amount of peptide in your vial, in milligrams (mg). This is printed on the vial label.
• Bacteriostatic Water — How much BAC water you added (or plan to add) during reconstitution, in milliliters (mL).

Step 3: Enter Your Desired Dose

• Desired Dose — The amount you want per injection.
• Dose Unit — Select micrograms (mcg) or milligrams (mg). BPC-157 is typically dosed in mcg. TB-500 and tirzepatide are dosed in mg.

Step 4: Select Your Syringe

• 100-unit (1 mL) — Most common. Tick marks every 2 units.
• 50-unit (0.5 mL) — Better precision for small doses. Tick marks every 1 unit.
• 30-unit (0.3 mL) — Best precision. Tick marks every 0.5 units.

Step 5: Read Your Results

• Concentration — How much peptide per mL of solution after reconstitution.
• Volume Per Dose — The exact mL to draw per injection.
• Syringe Units — The number to draw to on your insulin syringe. This is the number you actually use.
• Doses Per Vial — How many total injections you’ll get from one vial.

The syringe diagram below the results shows exactly where to fill to on your syringe.

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Understanding the Math

You don’t need this section to use the calculator, but understanding the math helps you double-check your work.

Concentration

Concentration = Peptide Amount (mg) ÷ Water Added (mL)

Example: 5 mg peptide + 2 mL BAC water = 2.5 mg/mL (or 2,500 mcg/mL)

Volume Per Dose

Volume = Desired Dose ÷ Concentration

Example: 250 mcg dose ÷ 2,500 mcg/mL = 0.1 mL

Syringe Units

On a standard 100-unit (1 mL) insulin syringe, 1 mL = 100 units. So:

Units = Volume (mL) × 100

Example: 0.1 mL × 100 = 10 units. Draw to the 10 unit mark on your syringe.

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Quick Reference: Common Peptide Dosing

Peptide	Vial Size	BAC Water	Dose	Syringe Units
BPC-157	5 mg	2 mL	250 mcg	10 units
BPC-157	5 mg	2 mL	500 mcg	20 units
TB-500	5 mg	2 mL	2.5 mg	100 units
TB-500	5 mg	2 mL	750 mcg	30 units
Tirzepatide	10 mg	2 mL	2.5 mg	50 units
Tirzepatide	30 mg	3 mL	5 mg	50 units

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Tips for Accurate Dosing

• Read at eye level. Hold the syringe horizontally at eye level to read the meniscus (the bottom curve of the liquid line). Reading from above or below gives inaccurate measurements.
• Use the right syringe. For doses under 20 units, a 50-unit or 30-unit syringe gives better precision than a 100-unit syringe.
• Be consistent with BAC water. Always add the same amount of BAC water each time you reconstitute the same peptide. This keeps your concentration and your dose math consistent.
• Account for dead space. Insulin syringes have minimal dead space, but low dead volume (LDV) needles waste even less. For expensive peptides, this matters.
• Store reconstituted vials properly. Refrigerate at 2–8°C. Use within 4–6 weeks. Never freeze a reconstituted vial.

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Related Guides

• Reconstitution Guide — Full step-by-step reconstitution technique, storage guidelines, and peptide-specific handling notes.
• Equipment Guide — Everything you need to get started, with budget breakdowns.
• BPC-157 Complete Guide — Dosing protocols, research overview, and practical usage.
• TB-500 Complete Guide — Loading and maintenance protocols, stacking with BPC-157.

Frequently Asked Questions

How do I calculate peptide syringe units?

Three numbers drive it: how much peptide is in the vial, how much bacteriostatic water you added, and the dose you want. Divide the peptide amount by the water volume to get concentration (mg per mL), then divide your dose by that concentration to get the volume to draw. On a U-100 insulin syringe each mL is 100 units, so multiply that volume by 100. The calculator above runs all of this and draws the fill line for you.

How many units on an insulin syringe is my dose?

It depends on your concentration, not the dose by itself. A U-100 insulin syringe holds 100 units per mL, so 0.25 mL reads as 25 units. Enter your vial size, your water, and your dose above, and the calculator returns the exact unit mark plus a diagram of where the fill line sits.

How much bacteriostatic water should I add?

There is no single correct amount. More water dilutes the solution, which spreads your dose across more syringe units and makes it easier to measure. Less water concentrates it. Common choices are 1 mL, 2 mL, or 3 mL per vial. Pick an amount, enter it above, and the calculator shows whether your target dose lands on a clean, readable unit mark.

Does this work for tirzepatide, semaglutide, and other GLP-1s?

Yes. The math is identical for any lyophilized peptide, GLP-1s included. Use the Tirzepatide preset or type your own vial size and dose. The calculator works from the milligrams, the water, and the dose you enter, not from which compound it is.

What if my vial size or dose is not a preset?

Enter your own numbers. The BPC-157, TB-500, and Tirzepatide presets are just shortcuts for common vial sizes. Type any peptide amount, any water volume, and any dose, in mcg or mg, and the calculator handles it.

Should I draw a larger or smaller volume per dose?

Larger volumes are easier to measure precisely, because the fill line lands on a clearer mark and small errors matter less. If your dose comes out to only a unit or two, add more bacteriostatic water so the same dose spreads across more units. For very small doses, a 30-unit or 50-unit syringe reads more accurately than a 100-unit.

This calculator is for research and educational purposes only. It is not medical advice. Always consult a qualified healthcare professional before using any peptide.