Insulin Syringe Units to mL Chart (U-100)

Insulin syringe units to mL chart (U-100)

Every value below is the number of units divided by 100, because a U-100 syringe holds 100 units in 1 mL.¹² These are scale readings, the volume that each printed mark represents at U-100. They are not doses.

Some U-100 syringes carry half unit marks. On those, 0.5 unit is 0.005 mL. Half unit syringes are described both in the accuracy research and in Vietnamese retail listings;¹²²⁵ the standard 1 mL syringe is marked in 1 unit notches.¹ The research does not give a fixed graduation interval for the 0.3 mL or 0.5 mL barrels, so this page does not state one.

How many units are in 1 mL, 2 mL and 3 mL

Going the other way, multiply the millilitres by 100 at U-100.² One millilitre is 100 units, a full 1 mL syringe. Anything above 1 mL is more than a single insulin syringe holds, since the largest insulin barrel is 1 mL.⁸

The 2 mL and 3 mL rows answer the "2 mL of BAC water" question directly. On a U-100 scale that is 200 and 300 units, but it describes a volume you add to a vial or draw across several fills, not a vial you can buy. US bacteriostatic water is not sold in a 2 mL or 3 mL vial: across the four current FDA labels the containers are 30 mL vials and a 20 mL fill in a 30 mL vial.¹⁰ Bacteriostatic water is defined by its benzyl alcohol preservative and by being a multiple dose container, not by any dose.¹⁰ To turn a vial mix into a per dose volume, use the reconstitution calculator and the bac water vs sterile explainer.

Insulin syringe barrel sizes in units

Insulin syringes come in three barrel capacities, all confirmed in the FDA device records and in a peer reviewed bench test.⁸⁹ At U-100 each capacity maps straight to a unit count.

The device records also print the strength restriction on the syringe itself, for example "U-100 Insulin Only".⁸ A syringe is a device, not a drug: US regulators class it as a Class II piston syringe, a calibrated barrel with a movable plunger, and 65 clearances match the device name "insulin syringe".⁶⁷

What a U-100 insulin syringe is

A U-100 insulin syringe is a calibrated piston syringe marked in insulin units instead of millilitres, and its scale is only correct for insulin at 100 units per millilitre.¹ MedlinePlus puts the identity plainly: standard insulin contains 100 units in 1 millilitre, this is also called U-100 insulin, and most insulin syringes are marked for U-100.¹ The same 100 units per mL identity is stated on current FDA labels for insulin human, and the same figure appears for insulin lispro and insulin glargine.²³⁴

cc and mL are the same volume, so a 1 cc syringe and a 1 mL syringe hold the same amount. A Vietnamese pharmacy spells it out as 5cc = 5 cubic centimetre = 5 milliliter, and FDA device records use both "cc" and "ML" for the same product family.²²⁸

Reading the scale, and where it goes wrong

The chart is simple arithmetic, but the reading is where error hides. A bench study that dispensed 1, 2 and 5 unit volumes 15 times per device found syringes were, in its words, "dangerously inaccurate, clinically, at the 1-unit dose", and finer half unit markings did not improve accuracy or precision.¹² With real users, 32 patients and 16 parents measuring three times each, the absolute error below 5 units was about 9.9% with syringes against 4.9% with pens, while above 5 units the two were close, about 3.2% against 2.2%.¹³ Small volumes are simply harder to measure, and a separate test of 30 people preparing 180 syringes of sterile water found clinically significant errors of at least ±20% are common when the volume is very small.¹⁷

The unit is also widely misread. A survey of 68 nurses and midwives found only 51.5% correctly defined the notion of a unit, and on a concentrated insulin case 35% multiplied the dose by two while 24% divided it by two.¹⁴ Concentration mismatch is a recognised hospital hazard. Subcutaneous insulin is classed as a high risk medication, and one hospital program moved dispensing from tuberculin syringes to U-500 insulin syringes to control the risk.¹⁵ MedlinePlus records the practice that creates the confusion in the first place, that because U-500 syringes can be hard to find, a provider may give instructions for using U-500 insulin with U-100 syringes.¹

Two more error sources are worth naming. Dead space in the barrel produced errors that exceeded 100% at low doses when two insulins were mixed in one syringe.¹⁶ Separately, the Humulin R label states a mixing order, regular insulin drawn first.² And simply seeing the marks is a limit for some people: NIDDK notes patients who cannot read the markings on the syringe, and MedlinePlus notes magnifiers that clip on to make them easier to see.¹¹¹

When the "units" are really hundredths of a millilitre

The reason a units to mL chart matters beyond insulin is that a U-100 syringe is often used to measure other liquids by volume. When it is, the "units" are read as hundredths of a millilitre, not as drug units. A published paediatric study did exactly this: it used a standard U-100 insulin syringe to measure glucagon, reading 2 syringe units as 20 micrograms and 15 syringe units as 150 micrograms of glucagon at the concentration it used (trial dose, not a recommendation, PMID 11315823).¹⁹

That is the whole point of the chart. The syringe measures a volume. What that volume contains depends entirely on the concentration in the vial, which is a separate calculation the reconstitution calculator handles.

Insulin syringes in Vietnam

Vietnamese pharmacy chains file these under names like "Bơm tiêm tiểu đường", "Kim tiêm tiểu đường" and "Bơm tiêm insulin". The unit word is "đơn vị" and the graduation marks are "vạch chia". A patient education page defines the standard as "U-100, nghĩa là có 100 đơn vị insulin trên một mililit chất lỏng", framed as the most common strength in the United States rather than a claim about Vietnam.²⁵

The most useful local fact for this chart is that both scales are on the shelf. Long Châu lists the red B.Braun Omnican 1ml/40iu (a U-40 syringe) and the orange Omnican 1ml/100IU (U-100), same brand, same 1 mL barrel, same box of 100, both at 360.000đ per box (captured 2026-09-06).²⁰²¹ Pharmacity lists the same orange U-100 Omnican at 360.000 ₫ (captured 2026-09-06).²⁴ Two syringes, identical barrel volume, same price, scales 2.5 times apart. That is exactly the swap the U-100 label on this chart is meant to prevent.

Other stock is U-100 as well. Long Châu lists a Vinahankook 1ml/100IU at 240.000đ per box and a 0.5 mL Promisemed syringe at 250.000đ per box (captured 2026-09-06).²³²² The Pharmacity patient education page also notes that U-40 insulin lingers in veterinary care, which is where a bench comparison that named both a U-40 and a 0.3 mL, 30 unit syringe also sat, though that study dosed no animals; its abstract records its animals section as "None".²⁵¹⁸ Prices are a 2026-09-06 snapshot and move.

A note on side effects

An insulin syringe is a device, and the sources here report no adverse effect of the syringe itself. The harms in the record belong to insulin and to measurement error, not to the barrel. FDA labelling lists hypoglycaemia as the most common adverse reaction to insulins, notes that severe, life threatening allergy including anaphylaxis can occur, and that insulins shift potassium and can lead to hypokalaemia; after U-500 specifically, severe hypoglycaemia may develop as long as 18 to 24 hours after an injection.⁵

Two device level cautions carry across from the labels: do not share a needle or syringe between people,² and where the liquid is bacteriostatic water rather than insulin, the benzyl alcohol preservative has been associated with toxicity in neonates and intravenous administration without a solute may cause haemolysis.¹⁰ The measurement error above is itself the reported harm mechanism, the inaccuracy at the 1 unit end of the scale and the dead space errors that exceeded 100% at low doses.¹²¹⁶

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