What it’s for
For amounts up to 50 units (0.5 mL), read to a single unit. Smaller amounts read more easily on the 0.3 mL; larger ones need the 1 mL, which is marked every 2 units.
What to check in the listing
Confirm the listing says U-100 and that syringes come individually wrapped, not loose in a bag. Barrel colour is cosmetic — brands use it to tell their own sizes apart, so match the numbers, not the colour.
At a glance
TypeInsulin syringe
Gauge31GGauge is the needle's thickness. A higher number is a thinner needle: 31G is thinner than 30G. Glossary Capacity0.5 mLCapacity is how much liquid the barrel holds. Smaller barrels have more space between the lines, so small amounts are easier to read. Glossary MarkingsU-100Markings are the scale printed on the barrel. U-100 means 100 units to the millilitre, so one unit is 0.01 mL; a mL scale is marked in tenths or fifths of a millilitre, depending on the barrel. Glossary Smallest line1 unitSmallest line is what one line on the barrel is worth. Half-unit lines let you read 0.005 mL; a 1 mL syringe is usually marked in 2-unit steps. Glossary Needle length8 mmNeedle length is how long the needle is. 4–8 mm (5/32–5/16 in) is common for under-the-skin use, and 13 mm (1/2 in) insulin syringes are used under the skin too; muscle needles are usually 25 mm (1 in) or longer. Glossary Needle connectionFixed needleNeedle connection is how the needle attaches. Fixed means it is built in (least dead space). Luer-lock screws on and cannot pop off. Luer-slip pushes on. None means there is no luer fitting at all — a pen needle screws onto the pen's own thread. Glossary Needle includedYes
TipSharpTip is the shape of the needle's point. A blunt tip is far less likely to stick you while mixing and drawing up, but it is still a sharp that can go through skin under force. Never for injecting.
Dead spaceLowDead space is the liquid left in the hub after the plunger bottoms out. Fixed-needle insulin syringes have almost none. Glossary Used forUnder-the-skin injections, Measuring small amountsUsed for lists the situations this product is for; the decision tool and the Finder match on these.
PriceBudgetPrice tier is the rough position within its category, not a live price: budget is the cheapest sensible option, premium costs more for a reason the page explains.
TravelCarry-on friendlyTravel says whether it is practical to fly with: carry-on means it goes through security without fuss.
SterileYesSterile means individually sealed and sterile until opened; anything that touches the inside of a vial or your skin should be.
Pack100Pack is how many come in the listing this site links to; it is shown only where every store's listing gives the same count. Check it against the listing, since photos often show ten and ship one.
ReusableNo
Specifications above were recorded from the Amazon listing on 2026-09-03. Listings change hands: open the listing for its current description, price and availability.
If the numbers in a syringe listing don't mean much yet, read 0.3, 0.5 or 1 mL insulin syringe: which size to buy first. The side-by-side 31G vs 30G comparison covers the other half of the choice.
Same thing, different spec
Compare these side by side
- Category
- Syringes & Needles
- Also useful
- Build a full kit →
Tools for this: Reconstitution calculator · Narrow this category by specification · Compare side by side