How to Use a Peptide Calculator: Concentration, Dosing & Reconstitution Guide

Why Peptide Calculations Matter

Accurate concentration calculation is foundational to reproducible peptide research. A small error in reconstitution volume — using 2mL of BAC water instead of 1mL — halves your working concentration and invalidates any comparison with previous experiments or published literature using different volumes.

This guide covers everything needed to calculate reconstitution volumes, working concentrations, and per-dose volumes for any research peptide, with worked examples using peptides available from Peptide Warehouse.

The Core Equation

All peptide concentration calculations use one equation:

Concentration (mg/mL) = Amount of peptide (mg) ÷ Volume of diluent added (mL)

Or rearranged to find volume needed for a target concentration:

Volume needed (mL) = Amount of peptide (mg) ÷ Target concentration (mg/mL)

This is straightforward, but the units matter. Research protocols often specify doses in micrograms (mcg), so it's important to keep track of unit conversions:

• •1 mg = 1,000 mcg
• •1 mL = 1,000 μL (microlitres)

Step 1: Know What You're Starting With

Before calculating anything, identify:

1. Peptide amount in the vial — e.g., 10mg, 50mg, 100mg

2. Target concentration — what mg/mL you want to work with

3. Diluent — always use pharmaceutical-grade bacteriostatic water (BAC water) for research peptides

A 10mg vial of BPC-157 contains 10 milligrams of lyophilised peptide. A 50mg vial of GHK-Cu contains 50mg. The numbers matter.

Step 2: Calculate Reconstitution Volume

Choose your target concentration, then calculate how much BAC water to add:

Volume (mL) = Peptide amount (mg) ÷ Target concentration (mg/mL)

Worked example 1: BPC-157 10mg

You want a working concentration of 5mg/mL:

Volume = 10mg ÷ 5mg/mL = 2mL BAC water

You want a working concentration of 10mg/mL:

Volume = 10mg ÷ 10mg/mL = 1mL BAC water

Worked example 2: GHK-Cu 50mg

You want a working concentration of 10mg/mL:

Volume = 50mg ÷ 10mg/mL = 5mL BAC water

You want a working concentration of 5mg/mL:

Volume = 50mg ÷ 5mg/mL = 10mL BAC water

Worked example 3: Retatrutide 10mg

You want a concentration of 2mg/mL for lower-concentration work:

Volume = 10mg ÷ 2mg/mL = 5mL BAC water

Step 3: The Full Reconstitution Reference Table

Step 4: Calculate Volume Per Dose

Once your peptide is reconstituted at a known concentration, calculate the volume of reconstituted solution needed for a specific dose:

Volume (μL) = Dose (mcg) ÷ Concentration (mcg/μL)

Since 1mg/mL = 1mcg/μL (the units conveniently align):

Volume (μL) = Dose (mcg) ÷ Concentration (mg/mL)

Worked example: BPC-157 at 5mg/mL concentration

Worked example: GHK-Cu at 10mg/mL concentration

Step 5: Reading a Syringe for Small Volumes

Standard 31G insulin syringes are typically 0.5mL or 1mL capacity with 0.01mL (10μL) graduations. Reading small volumes:

• •0.1mL on an insulin syringe = 10 units on a U-100 syringe
• •0.05mL = 5 units
• •0.025mL = 2.5 units

For very small volumes (under 20μL), measurement accuracy improves significantly with smaller syringe barrel diameters. Standard 0.5mL insulin syringes are preferable to 1mL syringes for this reason.

When working with Semax 10mg or other peptides at low working concentrations, verify the syringe graduation interval carefully before drawing any volume.

Step 6: Dilution Calculations (Serial Dilutions)

Sometimes you need to prepare a lower concentration from a stock solution without reconstituting from powder again. Use the dilution equation:

C1 × V1 = C2 × V2

Where:

• •C1 = stock concentration
• •V1 = volume of stock to use
• •C2 = target (final) concentration
• •V2 = total final volume

Example: Diluting Retatrutide from 10mg/mL to 1mg/mL

You need 1mL total at 1mg/mL. Starting from 10mg/mL stock:

V1 = (C2 × V2) ÷ C1 = (1mg/mL × 1mL) ÷ 10mg/mL = 0.1mL stock + 0.9mL BAC water

Step 7: Calculating How Long a Vial Lasts

With your concentration and per-dose volume established:

Number of doses = Total volume in vial ÷ Volume per dose

Example: BPC-157 10mg reconstituted with 2mL BAC water at 5mg/mL

• •Total volume: 2mL = 2,000μL
• •Dose volume at 250mcg: 50μL
• •Number of doses: 2,000 ÷ 50 = 40 doses

Reconstituted peptides stored at 2–8°C are typically stable for up to 4 weeks. Plan your research to consume the reconstituted vial within this window. If 40 doses exceeds what you'll use in 4 weeks, consider reconstituting with a smaller volume so each vial can be used up within the stability window.

Common Peptide Calculator Reference: Our Products

Supplies Needed for Reconstitution

• •BAC Water 10mL — one 10mL vial covers multiple reconstitutions
• •Insulin Needles 31G — use one needle to draw BAC water, a separate needle to inject into the peptide vial (one per access)
• •Alcohol wipes and a clean work surface
• •Permanent marker for labelling vials with compound name, concentration, and date

See our step-by-step reconstitution guide for the full technique, including how to inject without disrupting the lyophilised cake.

Quick Reference Conversion Table

Disclaimer: All calculations and information are provided for educational purposes related to in-vitro laboratory research. Not medical advice. Products are for research use only — not for human consumption, therapeutic use, or veterinary use.