The U-100, 1 mL barrel

100 units to the millilitre, 100 units of capacity, marked every 1 unit. Everything below is computed from those three figures.

Educational arithmetic only. Not medical advice and not a dosing protocol.

The three numbers every other figure on this page comes from. All three are printed on the barrel itself, so none of them is a claim this page is making.
Property	Value
Units to the millilitre	100
Capacity	1 mL, which is 100 units
Smallest printed mark	1 unit, which is 10.0 microlitres
Half a mark	5.0 microlitres

What the bench will not tell you

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. the limits of this bench.

What is particular to this barrel

This is the default assumption almost every calculator on the open web makes without saying so, and it is the one barrel where that assumption is harmless, because it is the one being assumed. A hundred units to the millilitre, marked every single unit, a full millilitre of capacity: the most forgiving of the five, and the reason the other four are dangerous. A tool that silently assumes this barrel is right often enough that nobody checks.

With a hundred marks over a millilitre, every tenth of a millilitre is ten clear graduations, which is why so much of this arithmetic is discussed in tenths.

Every row is computed from this barrel's own calibration of 100 units to the millilitre. The last column is half a graduation as a share of that draw, which is the smallest reading error the barrel can have at that point on its scale.
Reading, units	Volume, mL	Volume, microlitres	Half a mark, as % of the draw
5.0	0.050	50	10.00%
10.0	0.100	100	5.00%
20.0	0.200	200	2.50%
30.0	0.300	300	1.67%
40.0	0.400	400	1.25%
50.0	0.500	500	1.00%
70.0	0.700	700	0.71%
80.0	0.800	800	0.63%
90.0	0.900	900	0.56%
100.0	1.000	1000	0.50%

Where the reading error stops being ignorable

Half a graduation on this barrel is 5.0 microlitres, and that figure does not change with the size of the draw. As a share of the draw it therefore grows as the draw shrinks: at 2 units it is 25.0%, and it keeps climbing from there.

Below two graduations every tool on this bench flags the reading rather than printing it plainly, because at that point the uncertainty in the measurement is a large fraction of what is being measured and the precision of the arithmetic has stopped meaning anything. The fix is not a better calculation. It is more liquid, which is what thinning a solution is for.

The same printed number read on all five barrels. U-100, 1 mL is one column of this table, and the spread across the row is the reason no tool here defaults the barrel for you.
Printed reading	U-100, 1 mL	U-100, 0.5 mL	U-100, 0.3 mL	U-50, 0.5 mL	U-40, 1 mL
5 units	0.050 mL	0.050 mL	0.050 mL	0.100 mL	0.125 mL
10 units	0.100 mL	0.100 mL	0.100 mL	0.200 mL	0.250 mL
20 units	0.200 mL	0.200 mL	0.200 mL	0.400 mL	0.500 mL
30 units	0.300 mL	0.300 mL	0.300 mL	past the barrel	0.750 mL
40 units	0.400 mL	0.400 mL	past the barrel	past the barrel	1.000 mL
50 units	0.500 mL	0.500 mL	past the barrel	past the barrel	past the barrel

What this page is not saying

Everything here is a property of a manufactured object: how it is marked, how much it holds, and what follows arithmetically from those two facts. Nothing on this page says which barrel anybody should use, what should go in it, or what any reading on it should be. A calibration is a measuring scale, and a measuring scale has no opinion about what is measured with it.

Next to this on the bench

The barrel reading tool
This barrel, any volume, either direction.
The other four barrels
Same treatment, different three numbers.
Rounding to the nearest mark
The reading-error arithmetic in full.