How do I convert mL to IU on a U-100 syringe?

For U-100 syringes: IU = mL × 100. Example: 0.2 mL = 20 IU. Simply move the decimal point two places to the right.

What size syringe should I use for peptide injections?

Most peptide researchers use 1 mL (100 IU) U-100 insulin syringes with 27–31 gauge needles. Shorter needles (4–6 mm) are used for subcutaneous injection.

Syringes

How to Read an Insulin Syringe for Peptide Dosing

Q: What does IU mean on a syringe?

IU (International Units) is the scale printed on U-100 insulin syringes. For a 1 mL U-100 syringe, 100 IU = 1 mL. So 10 IU = 0.1 mL, and 50 IU = 0.5 mL. ASCEND shows your draw in both mL and IU so you can read it directly.

U-100 insulin syringes have IU markings, not mL. This confuses nearly every first-time researcher. Here's how to read them correctly every time.

TL;DR — On a U-100 syringe, 10 IU = 0.1 mL. Multiply your draw volume (mL) by 100 to get the IU mark. ASCEND shows both automatically.

The Key Formula

mL to IU Conversion

A U-100 (standard insulin) syringe has 100 IU per mL. The relationship is simple:

mL → IU (U-100 Syringe)

IU = mL × 100

Example: 0.2 mL = 20 IU on the syringe scale

IU → mL (U-100 Syringe)

mL = IU ÷ 100

Example: 20 IU = 0.2 mL

Quick Reference

IU to mL Conversion Table

IU Mark	Volume (mL)	Common Use
5 IU	0.05 mL	Very small doses
10 IU	0.10 mL	Small doses
20 IU	0.20 mL	500 mcg at 2500 mcg/mL
25 IU	0.25 mL	Common draw volume
50 IU	0.50 mL	Half syringe
100 IU	1.00 mL	Full 1 mL syringe

Worked Example

Finding Your Draw Volume

Say you want 500 mcg of BPC-157 from a 5 mg vial reconstituted with 2 mL BAC water:

Step 1 — Concentration

5,000 mcg ÷ 2 mL = 2,500 mcg/mL

Step 2 — Volume needed

500 mcg ÷ 2,500 mcg/mL = 0.2 mL

Step 3 — Syringe mark

0.2 mL × 100 = draw to 20 IU

ASCEND's calculator does all three steps automatically. Enter your vial size, BAC water volume, and desired dose — it shows the exact IU mark.

FAQ

Common Questions

What does IU mean on a syringe?

IU stands for International Units — it's the scale on insulin syringes. For U-100 syringes, 100 IU = 1 mL. So 10 IU = 0.1 mL. ASCEND shows your draw volume in both mL and IU marks.

What syringe size should I use?

Most peptide researchers use 1 mL (100 IU) U-100 insulin syringes with 27–31 gauge needles, 4–8 mm length for subcutaneous injection. Shorter, thinner needles reduce injection site discomfort.

What if my syringe has 0.5 mL capacity?

0.5 mL (50 IU) syringes are also U-100, so the IU-to-mL ratio is identical. They offer finer gradations, making them good for precise small doses. The formula is the same: IU = mL × 100.

Can I reuse syringes?

Syringes are single-use medical devices. Reusing needles dulls the tip and increases infection risk. Always use a fresh syringe for each injection.

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