Syringe Types and Scales
Nearly all peptide protocols use insulin syringes — designed for small, precise volumes with thin-gauge needles (29G–31G) appropriate for subcutaneous injection. Insulin syringes are labeled by two characteristics: total capacity and unit scale.
U-100 Syringe (1 mL)
Most CommonThis is the default syringe referenced in most protocol pages and the one most reconstitution math examples use.
U-100 Syringe (0.5 mL)
Half-sizeMarkings are physically more spread out, making small volumes easier to read accurately. Preferred for doses under 30 units.
U-100 Syringe (0.3 mL)
MicroIdeal for high-concentration reconstitutions or peptides dosed in the low-microgram range.
U-50 Syringe
Less commonBecause U-50 and U-100 (0.5 mL) syringes both hold 0.5 mL and each unit = 0.01 mL, the volume drawn at any given unit mark is identical. The difference is labeling only.
How to Read a Syringe
Identify the syringe type
Check the packaging or barrel print. It will say 'U-100,' 'U-50,' or 'U-20' and indicate total capacity (1 mL, 0.5 mL, or 0.3 mL). If it says 'U-100' and '1 cc' (cc = mL), you have the most common type.
Understand what the lines mean
On a U-100 1 mL syringe, each small line = 2 units (0.02 mL). Every fifth line is typically numbered (10, 20, 30...). On a U-100 0.5 mL syringe, each line = 1 unit (0.01 mL).
Read from the bottom of the plunger
The measurement is taken from the flat bottom edge of the rubber plunger stopper — not the top dome. Align the bottom edge with the line corresponding to your target volume.
Account for dead space
Fixed-needle insulin syringes have minimal dead space (typically 0.01–0.02 mL). For most peptide doses this is negligible, but be aware that the last drop in the needle hub is not delivered.
Unit Conversions
Peptide dosing involves four different "unit" systems that are often confused. Here's how they relate to each other.
| Unit | Meaning | Conversion |
|---|---|---|
| mg (milligram) | Mass of peptide | 1 mg = 1,000 mcg |
| mcg (microgram) | Mass of peptide | 1 mcg = 0.001 mg |
| mL (milliliter) | Volume of liquid | Depends on concentration |
| Units (syringe) | Tick marks on U-100 | 1 unit = 0.01 mL |
Worked Example
You have a 5 mg BPC-157 vial reconstituted with 2 mL BAC water. Your target dose is 250 mcg.
Draw to the 10-unit mark on a U-100 syringe.
Common Measurement Mistakes
Confusing 'units' with 'IU' (International Units)
Syringe 'units' are just tick marks on a U-100 scale (1 unit = 0.01 mL). IU is a biological activity measure used for hormones like HGH — they are not the same thing.
Reading from the top of the plunger dome
Always read from the flat bottom edge of the rubber stopper, not the rounded top. Reading from the dome will give you a smaller volume than intended.
Using a U-50 syringe but calculating for U-100
U-50 and U-100 (0.5 mL) syringes have the same volume per unit (0.01 mL), so the math is identical. Confusion usually arises from the different total unit counts.
Not accounting for concentration when switching BAC water volumes
If you change how much BAC water you add to a vial, the concentration changes and all your dose volumes change. Recalculate every time you adjust your reconstitution.
Research use only. All content on BlueFiveLabs is for educational and research purposes only. This is not medical advice. Consult a qualified healthcare professional before making any decisions involving peptides or any other compounds.