Peptide Dosage Calculator: The Reconstitution Math, Explained Once and For All

The single most common mistake in self-administered peptide protocols is dosing math. Vials are labelled in mg. Protocols are quoted in mcg. Syringes are marked in units. Reconstitution volumes vary. It's a recipe for 10× errors — and 10× errors with bioactive peptides are how protocols go badly wrong. Here's a clean peptide dosage calculator walk-through.

The three numbers you need

1. Vial size — how much peptide is in the vial (e.g. 5 mg)
2. Reconstitution volume — how much bacteriostatic water you add (e.g. 2 mL)
3. Target dose — what you want to inject (e.g. 250 mcg)

Step 1 — convert vial to mcg

Most vials are labelled in milligrams. Most protocols use micrograms. 1 mg = 1,000 mcg.

A 5 mg vial = 5,000 mcg of peptide.

Step 2 — calculate concentration

Concentration is just amount divided by volume:

5,000 mcg ÷ 2 mL = 2,500 mcg per mL.

Step 3 — calculate dose volume

Dose volume = target dose divided by concentration:

250 mcg ÷ 2,500 mcg/mL = 0.1 mL.

Step 4 — convert to insulin syringe units

Standard insulin syringes (used for SC peptide injections) are marked in 'units'. A standard U-100 insulin syringe has 100 units per 1 mL.

0.1 mL = 10 units on a U-100 insulin syringe.

Worked examples

BPC-157, 5 mg vial, reconstituted with 2 mL, 250 mcg dose

• Vial: 5,000 mcg
• Concentration: 5,000 ÷ 2 = 2,500 mcg/mL
• Dose volume: 250 ÷ 2,500 = 0.1 mL
• Syringe: 10 units

Ipamorelin, 5 mg vial, reconstituted with 2.5 mL, 300 mcg dose

• Vial: 5,000 mcg
• Concentration: 5,000 ÷ 2.5 = 2,000 mcg/mL
• Dose volume: 300 ÷ 2,000 = 0.15 mL
• Syringe: 15 units

TB-500, 5 mg vial, reconstituted with 5 mL, 2 mg dose

• Vial: 5,000 mcg = 5 mg
• Concentration: 5,000 ÷ 5 = 1,000 mcg/mL = 1 mg/mL
• Dose volume: 2,000 ÷ 1,000 = 2 mL
• Syringe: 200 units (or 2 mL on a larger syringe)

Reconstitution volume — practical guidance

Volume is your lever. Smaller reconstitution volume means more concentrated solution and smaller injection volume — but less precision on small doses. Larger volume means easier precise dosing but more liquid per injection. Sensible defaults:

• BPC-157 5mg: reconstitute with 2 mL → 2,500 mcg/mL
• Ipamorelin 5mg: 2.5 mL → 2,000 mcg/mL
• CJC-1295 no DAC 5mg: 2 mL → 2,500 mcg/mL
• TB-500 5mg: 5 mL → 1,000 mcg/mL (allows precise 2mg dosing)
• GHK-Cu 50mg: 5 mL → 10 mg/mL

Syringe selection

• SC injection: U-100 insulin syringe, 28–31 gauge, 0.5 mL barrel for most doses
• Larger SC doses (>50 units): 1 mL barrel insulin syringe
• IM injection: 25–27 gauge, 1 inch needle, 1 mL barrel — rarely needed for most peptide protocols

Sanity-check rules

1. Whenever your math says 'inject more than 50 units', re-check the concentration
2. Whenever your math says 'inject less than 2 units', re-check — you may need to reconstitute with more water for precision
3. Always check mg vs mcg twice. Twice.
4. Match the calculated dose against a published reference range. If you're 10× off, you've made a math error.