Barrel calibrations

Five barrels, three calibrations, five different answers to the same printed number. A page each, with every figure derived from the barrel rather than asserted about it.

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

U-100, 1 mL
100 units per mL, 100 units of capacity, marked every 1 unit.
U-100, 0.5 mL
100 units per mL, 50 units of capacity, marked every 1 unit.
U-100, 0.3 mL
100 units per mL, 30 units of capacity, marked every 1 unit.
U-50, 0.5 mL
50 units per mL, 25 units of capacity, marked every 1 unit.
U-40, 1 mL
40 units per mL, 40 units of capacity, marked every 1 unit.

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.

One printed number, five barrels. Every cell is computed from the calibration named in its column heading.
Reading	U-100, 1 mL	U-100, 0.5 mL	U-100, 0.3 mL	U-50, 0.5 mL	U-40, 1 mL
10 units reads as	0.100 mL	0.100 mL	0.100 mL	0.200 mL	0.250 mL
20 units reads as	0.200 mL	0.200 mL	0.200 mL	0.400 mL	0.500 mL
30 units reads as	0.300 mL	0.300 mL	0.300 mL	past the barrel	0.750 mL

Why this is the first reference family on the bench

Because it is the one place where a calculator can be confidently, invisibly wrong. Every other input on this bench is a number a reader types in and can check. The barrel is a physical object the software cannot see, and if it guesses, the answer it produces is wrong by a factor of two or two and a half with nothing in its appearance to suggest it.

So the barrel selector on every tool here starts empty and the tools refuse to proceed without it. That is a deliberate piece of friction, and it is the only field on the bench that has one.

What a calibration is and what it is not

A calibration is a statement about spacing: a U-100 barrel is marked so that a hundred of its units fill one millilitre. That is the entire content of the number. It says nothing about what the syringe contains, how strong it is, or what any reading on it ought to be.

Capacity is a separate fact and gets confused with calibration constantly. A U-100 barrel might hold 1 mL, 0.5 mL or 0.3 mL; all three are U-100, all three read the same number for the same volume, and only one of them can take 80 units. Both figures appear on every page here for exactly that reason.