Quick answer
The 1 mL syringe holds twice as much but is usually marked in 2-unit steps, so you cannot land on an odd number of units; the 0.5 mL is marked in single units. The 1 mL also comes with a slightly thicker 30G needle. If your draws stay at or under 50 units, the 0.5 mL is the more precise and more comfortable of the two.
Side by side
Rows that differ are highlighted. Values come from the product records for the two products named in the header.
0.5 mL Insulin Syringes 31G, 0.5 mL (100-count) |
1 mL Insulin Syringes 30G, 1 mL (100-count) |
|
|---|---|---|
| GaugeNeedle thickness. A higher number is a thinner needle: 31G is thinner than 30G. Glossary | 31G | 30G |
| CapacityHow much liquid the barrel holds. Smaller barrels have more space between the lines, so small amounts are easier to read. Glossary | 0.5 mL | 1 mL |
| MarkingsU-100 means 100 units to the millilitre, so one unit is 0.01 mL. A mL scale is marked in tenths. Glossary | U-100 | U-100 |
| Smallest lineWhat 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 | 1 unit | 2 units |
| Needle lengthLength of the needle. 4–8 mm is the usual range for under-the-skin use; longer is for muscle. Glossary | 8 mm | 8 mm |
| Needle connectionFixed means the needle is built in (least dead space). Luer-lock screws on and cannot pop off. Luer-slip pushes on. Glossary | Fixed needle | Fixed needle |
| Needle included | Yes | Yes |
| TipBlunt tips draw liquid from a vial without being able to go through skin; they are for mixing and drawing up. | sharp | sharp |
| Dead spaceLiquid left in the hub after the plunger bottoms out. Fixed-needle insulin syringes have almost none. Glossary | low | low |
| PriceRough position within its category, not a live price: budget is the cheapest sensible option, premium costs more for a reason the page explains. | Budget | Budget |
| TravelWhether it is practical to fly with: carry-on means it goes through security without fuss. | Carry-on friendly | Carry-on friendly |
| SterileIndividually sealed and sterile until opened. Anything that touches the inside of a vial or your skin should be. | Yes | Yes |
| PackHow many you get. Check this against the photo; Amazon listings often show ten and ship one. | 100 | 100 |
| Reusable | No | No |
Which should you choose?
- Pick 0.5 mL for draws up to 50 units: single-unit lines and the finer 31G needle.
- Pick 1 mL for draws over 50 units, or for drawing up water to mix a vial where 2-unit steps do not matter.
- If you own only one size, the 0.5 mL covers more everyday situations; keep a few 1 mL for mixing.
The products
Open in the comparison tool Find the right syringe
Related guides
- 0.3, 0.5 or 1 mL insulin syringe: which size to buy
- How to read an insulin syringe
- Mixing (reconstituting) a vial, step by step
Common questions
Why is a 1 mL syringe marked every 2 units?
There is not enough room on the barrel for 100 separate lines, so most brands mark every second unit.
Can I use a 1 mL insulin syringe to measure water for mixing?
Yes, and it is a good use for it; for water, 2-unit steps are more than fine.
Reviewed 2026-09-03. Equipment comparison only; nothing here is advice about what to inject or how much. Affiliate links open your own country's Amazon store; your price is the same.