Methodology

How DoseGauge calculates

DoseGauge is arithmetic you can check by hand. This page shows the exact formulas, a worked example, how the plasma curve works, and where every pharmacology figure comes from.

The reconstitution formula

Reconstitution is the step where you add bacteriostatic water to a vial of lyophilized (freeze-dried) peptide to make a liquid you can draw into a syringe. Given your vial strength and the volume of water you add, the rest is division:

concentration (mg/mL) = vial strength (mg) / BAC water (mL)
draw volume (mL)      = dose (mg) / concentration (mg/mL)
units (U-100)         = draw volume (mL) x 100
doses per vial        = floor( vial strength (mg) / dose (mg) )

That is the entire engine. Everything the calculator shows is one of these four results, computed at full precision from the numbers you enter.

A worked example

Suppose you have a 5 mg vial and you add 2 mL of bacteriostatic water, and your target dose is 0.25 mg:

Concentration: 5 mg / 2 mL = 2.5 mg/mL
Draw volume: 0.25 mg / 2.5 mg/mL = 0.10 mL
Units on a U-100 syringe: 0.10 mL x 100 = 10 units
Doses per vial: floor(5 / 0.25) = 20 doses

You can verify any result the calculator gives you with the same four lines.

Why units equal milliliters times 100

A U-100 insulin syringe is calibrated so that 1 mL contains exactly 100 units. The "units" on the barrel are not a measure of drug, they are a measure of volume: 1 unit = 0.01 mL. So once you know the draw volume in milliliters, multiplying by 100 gives the mark to draw to. DoseGauge reports that mark directly so you do not have to convert in your head.

How the plasma curve works

On compounds where it is meaningful, DoseGauge shows a simple plasma-concentration curve over time. It uses first-order elimination based on the compound's elimination half-life: after each half-life, the amount remaining halves. For repeated dosing, the curve adds each dose to what remains from previous doses to show approximate steady-state accumulation.

This model is a teaching aid, not a clinical pharmacokinetic simulation. It assumes a single compartment and ignores absorption rate, individual variation, and other real-world factors. It is meant to show the shape of accumulation, not to predict your blood levels.

We show the curve only when two things are true: there is a citable elimination half-life, and a multi-day accumulation curve is actually informative for how the compound is dosed. In practice that is the long-half-life weekly GLP-1s (for example semaglutide and retatrutide). For compounds with no validated human half-life, we show no curve and say so on the page.

Where the numbers come from

Every pharmacology figure on a compound page carries a visible source. We use a tiered standard:

Approved drugs: the FDA prescribing information, accessed through DailyMed (the U.S. National Library of Medicine label database). This covers compounds such as semaglutide, tesamorelin, and the bremelanotide product.
Investigational compounds: peer-reviewed literature and published clinical-trial data, cited to the specific paper, for compounds such as retatrutide.
Research peptides: where a compound is not FDA-approved and human data are limited, we say so plainly and cite the best available review articles. We do not present community protocols as recommendations.

About the default values

Each calculator pre-fills common vial sizes, water volumes, and a typical dose so you have something to start from. These defaults are reconstitution-reference conveniences, not dose recommendations. Change them to match your actual vial and your prescriber's instructions.

What we never do

DoseGauge computes from the values you enter. It never recommends a dose, never tells you what to take, and is not a substitute for your prescriber. For the full position, see our disclaimer.