Syringes & Units

SYRINGES

For peptides, you will inject subcutaneously—under the skin into fatty tissue. You will use insulin syringes with very thin needles that minimize injection pain. The standard is the U-100 Insulin Syringe. They are inexpensive and available on Amazon.

1. Volume and Capacity

Peptide doses are typically measured in units on an insulin scale as the injection volume is usually small. Units easily convert to milliliters (mL). The three most common sizes are:

  • 0.3 mL (30 Units): Best for micro-dosing or very small volumes. The markings are easiest to read on this size.
  • 0.5 mL (50 Units): The middle choice—standard for most peptide protocols.
  • 1.0 mL (100 Units): Used for reconstitutions or higher doses.

Dosages will be measured in milligrams(mg). Reconstitution water will be measured in milliliters(mL). Plan which syringes you’ll need by the dosages you’ll be taking and your reconstitution needs. If you will be doing a protocol with dosages of less than 1 milligram, using a 30-unit syringe will make it easier for you to fill the dosage accurately.

2. Needle Gauge (Thickness)

Since peptides are administered subcutaneously, the needles are very thin to minimize discomfort and tissue trauma.

  • The Rule: The higher the number, the thinner the needle.
  • Common Gauges: 29G, 30G, or 31G–the thinnest
3. Needle Length

Because you only need to reach the fatty tissue, the needles are much shorter than those used for vaccinations or muscle injections.

  • 5/16" (8mm): The most common length. It’s long enough to ensure the peptide stays in the fat layer but short enough to avoid hitting muscle.

The syringes you will use are SINGLE-USE ONLY. Do not attempt to use them more than once!
After use, use the syringe cap to bend the needle and effectively destroy the syringe before discarding it.

MILLILITERS, MILLIGRAMS & UNITS

Understanding the relationship between these three measurements is actually quite easy. The confusion usually stems from the fact that milligrams measure weight, while milliliters and units measure volume. To see the relationship, you’ll account for concentration.

1. Milliliters (mL) & Units

On a standard U-100 insulin syringe, milliliters and units are linked by a simple fixed ratio. The “U-100” designation literally means there are 100 Units per 1 mL of fluid.

  • 1.0 mL = 100 Units
  • 0.5 mL = 50 Units
  • 0.1 mL = 10 Units
  • 0.01 mL= 1 Unit
2. Milligrams (mg) & Milliliters (mL)

Now you need a little simple math. A milligram (mg) is the amount of actual peptide (the lyophilized powder) in the vial. It’s how much you bought, like 30mg of Tirzepatide or 10mg of BPC-157. When you reconstitute a peptide with bacteriostatic water (BAC water), you create a concentration.

Milligrams ÷ BAC water = Concentration in milligrams per milliliter

If you have a 10mg vial of a peptide and you add 2mL of water: 10 ÷ 2 = 5mg per mL

Doses smaller than 1mg are measured in micrograms(mcg). This is VERY small! There are 1000mcg in 1mg.
.5mg = 500mcg .25mg = 250mcg
To convert mcg to mg, divide by 1000: 250mcg ÷ 1000 = .25mg

3. Calculate your dose

The dose is in milligrams. The syringe is in units. You’ve reconstituted a peptide vial with milliliters of BAC water. How many units do you need to draw for your dose?

(Dose(mg) ÷ Total mg in the vial)  x  Units of BAC water = Dose in Units

Let’s say your dose is 2mg. Your vial of peptide is 10mg. You reconstituted with 2mL (200 units) of BAC water:
(2 ÷ 10)  x  200 = 40 You will draw 40 units of the peptide into the syringe. At that number of units, it should also be easy for you to figure out your peptide vial contains 5 doses of 40 units each.

Would you prefer to inject less fluid volume? Use 1mL (100 units) of BAC water to reconstitute.
(2 ÷ 10)  x  100 = 20 You will draw 20 units of the peptide into the syringe. At this number of units, your peptide vial contains 5 doses of 20 units each.

PRO TIPS

Two important things for you to know!

  • Except for peptides that sting, there is no particular amount of BAC water required for a particular peptide. As long as the amount of BAC water fully dissolves the peptide, you can choose to reconstitute with an amount of BAC water that will result in the injection volume you’re comfortable with. You can reduce large fluid volumes of high dosages. If a dosage is very small, you might reconstitute with an amount that you believe will be easy to draw accurately.
  • You don’t actually have to do the math yourself! There are many easy-to-use Peptide Calculators online. A personal favorite is Prime Peptide. You might also check how much more expensive Prime Peptide’s products are.
    (Spoiler Alert: 10mg of Tirzepatide from Prime Peptide costs MORE than a 30mg vial from Peptide Buyers Club!)

SUPPLIES

You can find what you need on Amazon. These are products I use myself.