Informational use only — not medical advice. For adults 21 and over. Talk to a qualified healthcare professional before making decisions about medications or supplements.

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U-100 vs U-50 insulin syringe for peptides

People worry the syringe changes the dose. It does not. Both scales are 0.01 mL per unit, so a dose that reads 6 units on a U-100 reads 6 units on a U-50. What changes is the ceiling, the tick spacing, and therefore how precisely you can read a small draw.

Informational use only — not medical advice. Check every figure against your own product and talk to a licensed healthcare provider before starting or changing anything.

Same unit, different barrel

	U-100	U-50	U-30
Capacity	1 mL (100 units)	0.5 mL (50 units)	0.3 mL (30 units)
Volume per unit	0.01 mL	0.01 mL	0.01 mL
Marks every	2 units	1 unit	1 unit (some 0.5)
Best for	Draws above 50 units, reconstitution water	Most daily peptide doses	Very small doses under 30 units

Which one for which dose

Look at where your usual draw lands. At the app's concentrations:

Ipamorelin 100 mcg is 4 units — comfortable on a U-50 or U-30, cramped on a U-100.
BPC-157 200 mcg is 6 units — fine on any of the three.
TB-500 2.5 mg is 75 units — U-100 only, or two U-50 draws.
Tirzepatide 2.5 mg at 10 mg/mL is 25 units — U-50 territory.

Dosify Me lets you set the syringe size per schedule and draws the barrel you actually own, with the fill line where your dose sits.

Needle length and gauge

Subcutaneous peptide injections use short, fine needles: 29 to 31 gauge, 5/16 inch (8 mm) or 1/2 inch (12.7 mm). The gauge does not affect the unit reading. Use a fresh needle every draw; a used tip dulls and drags. If you switch brands, check the cap colour against the printed gauge rather than trusting the colour alone, because colour codes differ between makers.

Questions people ask

Is a unit the same on a U-100 and a U-50 syringe?

Yes. Both are 0.01 mL per unit. A 10-unit dose is 0.1 mL on either. The U-50 simply stops at 50 units (0.5 mL) and spreads its marks further apart.

Which syringe should I use for small peptide doses?

A U-50 or a 0.3 mL U-30 syringe. A 4-unit ipamorelin dose on a U-100 sits between the first few marks; on a U-50 the same dose spans twice the distance and is easier to hit exactly.

Can I draw more than 50 units on a U-50?

No, and that matters for larger doses. A 2.5 mg TB-500 dose at 3.33 mg/mL is 75 units, which needs a U-100 or two draws on a U-50.

What does U-100 actually mean?

It is an insulin term: 100 units of insulin per mL. Peptide users borrow the syringe and the unit scale, not the insulin. Each unit is still 0.01 mL regardless of what is in the vial.

Dosify Me does this math for you. Pick the compound, your vial size and dose, and the app draws the exact syringe reading, keeps your schedule and reminders, and logs every dose — privately, on your phone.

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How many units is 250 mcg?
How much is 1 mL of testosterone cypionate? — mL to mg at each strength.
Reconstitution calculator — switch between U-100 and U-50 and watch the reading.

Pages for the compounds in this guide

Figures computed from the Dosify Me compound database on 2026-10-08.