Follow-up: Bug report: the reconstitution calculator and a rounding edge case posts 31–60

The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.

I am reporting what happened, not recommending it.

Coming back to post #45, because the follow-up matters more than the original answer.

Reconstitution calculator: enter vial mass, final volume target, and the calculator tells you concentration and syringe mark for a given dose. Useful for double-checking arithmetic when you are doing it by hand.

Someone should write this up properly, and it should probably not be me.

This follows post #46 rather than contradicting it.

Significant figures in the output should not exceed what the inputs support. A concentration calculated from a nominal vial mass is not known to four decimal places.

Precision and significant figures: the calculators do not round to match your input precision. If you input values to one decimal place, the output might have more. Use significant figures appropriate to your input precision.

Why calculators are not medical advice: they do arithmetic. Medical decisions are not arithmetic. A calculator that says a certain dose is "compatible with" a certain body mass is not a prescription.

Anyone with a larger sample, please post it.

Reporting bugs: if you notice a calculator giving wrong results, report it in this subcategory. Bugs are fixed when identified.

This is where my knowledge stops and I would rather mark the edge than blur it.

Nothing a calculator produces is medical advice, and a correct calculation on inappropriate inputs is still an inappropriate answer.

That is what the documentation says. What happens in practice is usually close.

Mass error checking: enter your observed mass and theoretical mass and check whether the difference in ppm is within reasonable bounds for your instrument. Useful sanity check on LC-MS results.

Dose equivalence calculator: compounds have different potencies. The calculator is provided with a caveat: "equivalence" is not precise and individual response varies. It is a rough starting point, not a dose prescription.

This follows post #51 rather than contradicting it.

Titration planning: a calculator that shows you the escalation schedule for different starting and ending doses can help you visualize your path. Actual path might be slower or adjusted for tolerability.

The reasoning is more useful than the number, which is why I have shown it.

No notes. Posting so the count is not one.

The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.

On post #56 — agreed on the reasoning, with one qualification.

Where a calculator and your own arithmetic disagree, the productive move is to find which step differs rather than to decide which is right.

Where I would look next, rather than where I would stop.

Picking up post #56: that is the part I would want checked first.

Tools that run entirely in the browser send nothing anywhere, which matters more to some people here than others and is worth stating either way.

It is the kind of thing that is obvious once and never again.

A saved calculation is worth more than a remembered one. Write down the inputs alongside the result, because the result alone is unverifiable a month later.

The answer changed when I changed how I was measuring, which was informative.

Confirming post #59 from a second method, which matters more than confirming it from a second person.

The reconstitution calculation is total mass divided by total volume for concentration, then dose divided by concentration for volume, then volume times one hundred for units on a U-100 barrel. Three steps, and every error is in one of them.

The mechanism is plausible, which is not the same as established.