Volume into units
The last step of the main conversion, on its own. A unit means nothing until you say which barrel, so the barrel is the first field.
Educational arithmetic only. Not medical advice and not a dosing protocol.
Before you act on that number
This is educational arithmetic on figures entered by the reader. It is not medical advice, not a dosing protocol, and not a recommendation that anything be prepared, obtained or administered.
Nothing here states what quantity is appropriate for anyone, and there is no function in it that produces an amount to administer. A question about anyone’s health belongs with a licensed clinician who can examine the person asking.
Compounds of the kind this arithmetic is used on are largely research chemicals that are not approved by the FDA for human use. An exact calculation is not an accurate measurement: what is actually in a syringe depends on the preparation and the device, neither of which this page can see.
No qualified clinical reviewer is recorded against this site, and no credential is claimed anywhere on it. what this is not, at full length.
| Volume | U-100, 1 mL | U-100, 0.5 mL | U-100, 0.3 mL | U-50, 0.5 mL | U-40, 1 mL |
|---|---|---|---|---|---|
| 0.05 mL | 5 | 5 | 5 | 2.5 | 2 |
| 0.1 mL | 10 | 10 | 10 | 5 | 4 |
| 0.2 mL | 20 | 20 | 20 | 10 | 8 |
| 0.3 mL | 30 | 30 | 30 | 15 | 12 |
| 0.5 mL | 50 | 50 | past the barrel | 25 | 20 |
| 1 mL | 100 | past the barrel | past the barrel | past the barrel | 40 |
The two numbers on a barrel that get confused
Calibration and capacity are different facts and both are printed on the syringe. Calibration is how many units fill a millilitre: 100, 50 or 40. Capacity is how much the barrel holds: 1 mL, 0.5 mL or 0.3 mL. A U-100 barrel can be any of those three capacities, and all three read the same number for the same volume.
Which means a reading can be arithmetically correct and physically impossible. Forty units is 0.4 mL on a U-100 whatever the capacity, and a 0.3 mL barrel cannot take it. The panel above flags that rather than printing a number the device cannot deliver.
Why the nearest mark is printed next to the exact figure
Because the exact figure is often unreachable. A barrel marked every single unit can show 7 units or 8 units; it cannot show 7.14. The exact value is still worth seeing, because the gap between it and the nearest mark is a real quantity and it is the reader's to judge.
Half a graduation on a 1 mL U-100 barrel is five microlitres, and that does not shrink when the draw does. At 20 units it is 2.5% of the measurement; at 2 units it is 25%. Below two graduations this panel flags the reading, and the honest fix is more liquid rather than more decimal places - which is what making a solution weaker is for.