Supplies · 2 min read

Insulin syringe guide

Almost every dosing error in peptide research traces back to the syringe: units confused with millilitres, or a barrel too large to read a small dose.

Open the dosage calculator

Units are not millilitres

A U-100 syringe is graduated in insulin units, where 100 units = 1 mL. So 1 unit = 0.01 mL. The syringe does not know what is inside it — the unit markings are simply a fine volume scale.

Units × 0.01 = millilitres. Millilitres × 100 = units. That is the whole conversion.

Choosing a barrel size

BarrelCapacityBest for
0.3 mL30 unitsSmall doses — finest graduations
0.5 mL50 unitsGeneral research use
1.0 mL100 unitsLarge volumes only

Use the smallest barrel that fits your dose. A 5-unit draw on a 100-unit barrel is far harder to read accurately than the same draw on a 30-unit barrel.

Gauge and length

31G is the common choice for subcutaneous work — thin enough to be comfortable, strong enough not to bend. Use a separate larger-bore luer-lock syringe for transferring bacteriostatic water so you do not blunt your insulin needles on the stopper.

  • Never reuse a needle — the tip dulls after one puncture.
  • Tap the barrel to clear bubbles before setting the final dose.
  • Read the plunger at the front edge of the black seal, not the tip.

Frequently asked questions

How many units is 0.25 mL?

25 units on a U-100 syringe.

What gauge syringe comes with Origen bundles?

31G U-100 insulin syringes, alongside a luer-lock syringe for reconstitution, alcohol pads, and bacteriostatic water.

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All Origen products are supplied for laboratory research use only and are not for human or veterinary consumption. Nothing on this page is medical advice. Last updated 2026-08-03.