Peptide calculator.

The peptide in the vial divided by the water added. A 5 mg vial in 2 mL of water is 2.5 mg per millilitre. The peptide's own volume is treated as nil, which is what every reconstitution calculator does and which sits far below anything a syringe can resolve.

The dose divided by that concentration. At 2.5 mg per millilitre, a 250 mcg dose is 0.1 mL. Halve the water and the concentration doubles, so the same dose becomes half the volume.

That volume read on the U-100 scale, where 100 units is 1 mL and one unit is 0.01 mL. So 0.1 mL is 10 units. A 0.3 mL barrel holds 30 of them, a 0.5 mL holds 50, and a 1 mL holds 100. U-40 and U-500 syringes are a different scale entirely and these numbers do not apply to them.

A dose that works out at 10.4 units falls between two markings on the barrel. Where that happens, the calculator names a water volume that would put the same dose on a whole unit instead. It only suggests volumes that fit in a real vial, and says nothing at all when none of them works.

Each draw costs the vial its dose plus 0.002 mL left behind in the needle, so a 0.1 mL dose takes 0.102 mL out of it. The water divided by that, rounded down, is the number of whole draws in the vial. Anything left under one draw stays in the vial, and it is reported rather than quietly rounded up.

The calendar is then counted, not estimated: the draws are spread across the days you say you draw on, and the answer is the stretch from the first draw to the last, counted inclusively. Where the days of the week are chosen it runs from the earliest of them, so starting on a different one of your days shifts the total slightly.