When you mix a vial, a wrong number is not a cosmetic bug. So the mixing & syringe converter in Embera was the first thing to get real tests.
What the converter does, and what it does not do
You enter the amount in your vial and the dose on your prescription. You pick the syringe mark you want your dose to land on. The converter tells you how much water to add, and shows the math:
10 mg ÷ 2 mL = 5 mg/mL → 2.5 mg = 0.5 mL = 50 units
It never suggests a dose. It is a unit conversion: mg to mL to syringe units. The dose is always yours, from your prescriber or pharmacy label.
Why it works backwards
Most mixing calculators ask how much water you added and hand you something like “17.3 units”. Nobody can draw 17.3 units accurately. It was a complaint we saw in peptide communities, in a thread with close to a hundred comments. So Embera asks where you want the dose to land (a clean mark like 25 or 50 units) and works out the water. The free web converter does both directions.
The 24 cases
The math is kept in one small, separate piece of code, so it can be tested on its own. Then 24 examples were worked out by hand, covering:
- Common vial sizes, from 2 mg to 60 mg
- Small starting doses like 0.25 mg and larger ones like 15 mg
- Every syringe mark offered, from 10 to 100 units
- Awkward numbers, like 0.75 mg from a 5 mg vial (3.33 mL of water) or 1.7 mg from a 12 mg vial
For each case, the test checks the water to add, the syringe units, and that the concentration times the volume gives back exactly the prescribed dose. These tests run every time the app is built. If a future change breaks one, the build fails before anyone sees it.
The guard rails
Tests prove the arithmetic. Guard rails catch results that are arithmetically right but unusable:
- The water does not fit. 10 mg, 0.25 mg dose and a full 1 mL draw means 40 mL of water, far more than a vial holds. The converter asks for your vial’s capacity and warns, crossing out the result.
- Too little to measure. Under 0.5 mL of water is hard to measure accurately with a mixing syringe. It warns and suggests a bigger mark.
- Unmeasurable decimals. 3.33 mL cannot be measured. It offers 3.3 mL instead and recalculates the units for the same dose: 49.5.
Each of these has its own test too.
The web version runs the same checks
The free mixing & syringe converter on this site uses a copy of the same formulas, and the same 24 cases run against it. If the app and the site ever disagreed, the site’s tests would fail.
What testing cannot do
Tests prove the converter does the math it was designed to do. They cannot check that the numbers you type are right, or that your syringe is U-100. Always check your pharmacy label and ask your pharmacist if a result surprises you.