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Peptide Units Converter

Convert any peptide dose between mg, mcg, mL, and insulin syringe units in seconds. Select your peptide, enter your concentration, and get the exact units to draw.

Jump to converterReconstitution calculatorBAC water calculator

How peptide unit conversion works

All standard insulin syringes sold in the US are U-100, meaning the syringe holds 100 units per mL of liquid. This means 1 unit = 0.01 mL, regardless of whether you're using a 0.3 mL (30-unit), 0.5 mL (50-unit), or 1.0 mL (100-unit) syringe. The only difference between syringe sizes is the maximum volume they hold.

To convert a peptide dose to syringe units, you need two pieces of information: your concentration (how many mg of peptide per mL of solution) and your desired dose in mg or mcg.

The formula

mL = dose (mg) ÷ concentration (mg/mL)

Units = mL × 100

Example

Semaglutide 0.25 mg dose, reconstituted at 2 mg/mL:

0.25 mg ÷ 2 mg/mL = 0.125 mL

0.125 mL × 100 = 12.5 units

Your concentration is determined during reconstitution — when you add bacteriostatic water (BAC water) to your peptide vial. A 5 mg vial with 2 mL of BAC water gives a concentration of 2.5 mg/mL. A 5 mg vial with 1 mL of BAC water gives 5 mg/mL. The more water you add, the more dilute your solution (and the more units you'll draw per dose).

To convert units to mg (the reverse direction), use the toggle in the tool above. The formula is: units ÷ 100 = mL; mL × concentration = mg dose. This is useful when your prescription lists a volume in units and you need to verify the mg equivalent.

U-100 insulin syringe reference

SyringeCapacityMax units1 unit =
0.3 mL syringe0.3 mL30 units0.01 mL
0.5 mL syringe0.5 mL50 units0.01 mL
1.0 mL syringe1.0 mL100 units0.01 mL

Frequently Asked Questions

How do I convert peptide mg to syringe units?
Divide your dose in mg by the concentration in mg/mL to get mL. Then multiply by 100 (since all insulin syringes are U-100: 1 unit = 0.01 mL). Example: 0.25 mg dose ÷ 2 mg/mL = 0.125 mL = 12.5 units.
What does 1 unit mean on an insulin syringe?
All standard insulin syringes are U-100, meaning 1 unit = 0.01 mL. A 100-unit syringe holds 1 mL total; a 50-unit syringe holds 0.5 mL; a 30-unit syringe holds 0.3 mL. The unit markings on all three syringes are identical — only the total capacity differs.
What is the difference between mg, mcg, and mL?
mg (milligrams) and mcg (micrograms) are units of mass — they describe how much peptide you're dosing. 1 mg = 1,000 mcg. mL (milliliters) is a unit of volume — it describes how much liquid you draw into the syringe. The conversion between mass and volume depends on your concentration (mg/mL).
How do I calculate concentration after reconstitution?
Divide the total peptide mass in the vial (mg) by the volume of bacteriostatic water you added (mL). For example, a 5 mg vial reconstituted with 2 mL of BAC water gives a concentration of 2.5 mg/mL. Use the BAC water helper in the tool above to calculate this automatically.
Does syringe size affect the unit calculation?
No — the math is the same regardless of syringe size. All insulin syringes are U-100 (1 unit = 0.01 mL). A smaller syringe (like 0.3 mL / 30 units) just has a lower maximum capacity. If your calculated dose exceeds the syringe capacity, the tool will warn you.
Can I use this tool for semaglutide and tirzepatide?
Yes. Select the semaglutide or tirzepatide preset from the dropdown. The tool will preload common concentrations for that peptide. For dedicated semaglutide and tirzepatide converters with dosing charts, see the peptide-specific pages linked below.

Related tools & guides

Peptide Reconstitution Calculator

Calculate syringe units from vial size, BAC water, and dose. Includes peptide presets.

Peptide Titration Calculator

Generate a week-by-week dose escalation schedule for GLP-1 and peptide protocols.

Semaglutide Units Converter

Dedicated units converter for semaglutide with common concentration presets and dosing chart.

Tirzepatide Units Converter

Dedicated units converter for tirzepatide with mg to units chart for 5–15 mg/mL concentrations.

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Medical disclaimer: This tool is provided for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Peptide dosing should be supervised by a licensed healthcare provider. All peptides referenced are for research purposes in regions where they are not approved for clinical use. Always consult your prescribing physician before adjusting any dose.