Insulin Syringe Units to mL: 0.3, 0.5 and 1 mL Chart

Every value below is the number of units divided by 100, because a U-100 syringe holds 100 units in 1 mL. 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. As arithmetic only, the same divide by 100 rule turns 1.5 units into 0.015 mL, 0.25 unit into 0.0025 mL and 0.1 unit into 0.001 mL, though a 0.25 or 0.1 unit step is finer than any mark described here. Half unit syringes are described both in the accuracy research and in Vietnamese retail listings; the standard 1 mL syringe is marked in 1 unit notches. 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.

Sources: MedlinePlus (NIH National Library of Medicine). Giving an insulin injection; openFDA drug label; PubMed 14968895; Pharmacity

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

Short answer: 2 mL of bacteriostatic water is 200 units on a U-100 scale, and 3 mL is 300 units. Both are more than a single 1 mL insulin syringe holds, so each is measured across more than one fill.

Going the other way, multiply the millilitres by 100 at U-100. 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.

Multiplying by 100 keeps working above 3 mL: 5 mL is 500 units, 10 mL is 1000 units, and 30 mL, the size of the US bacteriostatic water vials on the FDA labels, is 3000 units at U-100. In between values work the same way, so 0.125 mL is 12.5 units, 2.4 mL is 240 units and 2.5 mL is 250 units. An 80 mg KLOW vial mixed with 4 mL is a handy case: each unit then holds 125 mcg of GHK-Cu, as the KLOW peptide dosage chart sets out for all four parts. The divide by 100 rule also goes past 100 units: 120 units is 1.2 mL, 160 units is 1.6 mL, 240 units is 2.4 mL and 1000 units is 10 mL. A 1 mL syringe holds 100 units, so none of those unit counts fits in one fill.

On this U-100 scale there is no single 150, 200 or 300 unit insulin syringe. The largest barrel is 1 mL (100 units) and a 0.5 mL barrel holds 50 units, so 150 or 200 units takes two fills of a 1 mL syringe, 300 units takes three, and 2 mL on a 50 unit syringe (200 units) takes four fills. The unit is set by the insulin strength, not the device: on U-100 insulin 1 unit is 0.01 mL and 3 mL is 300 units, whether you draw it with a syringe or dial it on an insulin pen. Real vial math hits the same wall: in our cagrilintide dosage chart, a 5 mg vial mixed with 3 mL puts the two largest trial amounts past one 1 mL fill. Sermorelin hits it too: our sermorelin dosage calculator flags when 3 mL of water in a small vial pushes a draw past 100 units.

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. Bacteriostatic water is defined by its benzyl alcohol preservative and by being a multiple dose container, not by any dose.

Starting from a volume instead of a mark? Our mL to units guide runs every amount from 0.01 to 3 mL and shows how many fills of a 0.3, 0.5 or 1 mL barrel each one takes.

Disclosure: Some links on this page are referral links. Peptides Vietnam may earn a fee at no cost to you. Editorial content is never sold.

To turn a vial mix into a per dose volume, use the reconstitution calculator and the bac water vs sterile explainer. If you need the water itself, our supply partner Peptara Labs sells it: see the bacteriostatic water Peptara stocks.

Sources: openFDA drug label; openFDA device UDI (FDA GUDID), brand_name "insulin syringe"; openFDA drug labels

Insulin syringe barrel sizes in units

Insulin syringes come in three barrel capacities, all listed in the FDA device records. A 2023 study of a 3D printed autoinjector also used BD insulin syringes in the 1 mL, 0.5 mL and 0.3 mL sizes, filled with alcohol rather than insulin. At U-100 each capacity maps straight to a unit count. For needle length and gauge alongside these barrel sizes, see the insulin syringe sizes guide. To match a barrel size to a dose, our peptide calculator converts vial size and water volume into units.

The device records also print the strength restriction on the syringe itself, for example "U-100 Insulin Only". 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".

Sources: openFDA device UDI (FDA GUDID), brand_name "insulin syringe"; Selvaraj and others, autoinjector study tested with BD insulin syringes, PLoS One 2023, PMID 37450496; eCFR. 21 CFR 880.5860 Piston syringe, Class II; openFDA device 510(k) clearances, device_name "insulin syringe", 65 results

Insulin syringe chart by size, needle length and gauge

The converter at the top of this page lets you pick a barrel size, a needle length and a gauge, and shows what each means and whether makers sell that combination. It describes what is sold and what the research says. It does not pick a needle or a dose for you.

Needle gauge and length by syringe size

This table lists the gauges sold for each barrel size and needle length, from U-100 insulin syringes marked as in commercial distribution in the FDA device records, read on 2026-10-17.

A higher gauge number means a thinner needle. The 6 mm syringe needle comes only in 31G in these records. A few makers also list 27G needles (1 mL, 8 mm and 12.7 mm) and 32G needles (0.5 mL and 1 mL, 8 mm), which are outside the selector. One leakage study found 32G needles leaked less than 31G, but that result comes from pigs. Makers file these records, and openFDA says to treat its results as unvalidated, so read the box before you buy.

Sources: 26, 27, 36, 28, 1, 29, 30, 31, 32

Sources: 1, 5, 4, 20, 21, 33

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. 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. 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. Some syringe labels print IU instead of units, such as the 1ml/100IU on the orange Omnican, and for insulin 100 IU/mL means the same U-100 scale, so on that syringe 4 IU reads as 0.04 mL and 100 IU is 1 mL.

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.

Sources: 1, 2, 3, 4, 22, 34, 8

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. 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%. 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.

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.

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. 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.

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. Separately, the Humulin R label states a mixing order, regular insulin drawn first. 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.

Sources: 12, 13, 17, 14, 15, 1, 16, 2, 11

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, measuring glucagon with a standard U-100 insulin syringe at the concentration it used, and reported these trial doses:

2 syringe units = 20 micrograms of glucagon; 15 syringe units = 150 micrograms of glucagon

Disclaimer: these are trial doses from one study, shown only to illustrate reading syringe units as volume. They are not a recommendation or a dose for anyone reading this page.

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 vial concentration calculator handles. So how many units a microgram (mcg) or milligram amount takes on an insulin syringe depends on the vial: divide the amount by the concentration per mL to get mL, then multiply by 100 for U-100 units, remembering that 1 mg is 1000 mcg.

Two real vials show how far apart the answers land. In a 20 mg retatrutide vial mixed with 3 mL, every milligram takes 15 units, and our 20mg retatrutide bac water guide lists the units for each trial dose. A 100 mg GHK-Cu vial with 2 mL goes the other way, packing each milligram into 2 units, which the GHK-Cu bac water tables fix by adding more water. In a three-peptide GLOW vial, one unit is still 0.01 mL, yet it holds GHK-Cu, BPC-157 and TB-500 together; the GLOW peptide dosage chart lists the micrograms of each. For a GHK-Cu vial of any size, the GHK-Cu reconstitution calculator shows how each water volume changes the units per milligram.

Sources: PubMed 11315823

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.

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). Pharmacity lists the same orange U-100 Omnican at 360.000 ₫ (captured 2026-09-06). Two syringes, identical barrel volume, same price, scales 2.5 times apart, which 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). 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". Prices are a 2026-09-06 snapshot and move.

Sources: 25, 35, 20, 21, 24, 23, 22, 18

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.

Two device level cautions carry across from the labels: do not share a needle or syringe between people, 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. 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.

Sources: openFDA drug label. HUMULIN R U-500 KwikPen (insulin human injection), U-500; openFDA drug label; openFDA drug labels; PubMed 14968895; PubMed 7050644. Insulin syringes: dangers of dead space

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