Reconstitution, pen clicks, cost and accumulation
Peptides supplied as a freeze-dried powder have to be mixed before they can be drawn. These calculators do that arithmetic for you: how much bacteriostatic water to add, and exactly which mark on the syringe a given dose lands on. Everything runs in your browser and nothing you type is sent anywhere.
General information only. These tools perform arithmetic on figures you enter. They hold no dosing recommendations and do not know what is in your vial. Always check the label, and speak to a qualified healthcare professional about your own circumstances.
Every figure is arithmetic on what you selected. This tool does not know what is in your vial and does not suggest a dose. The values in each list are common ones, not recommendations. Check the label before you draw.
The pen in your hand
Why this tool exists. A branded pen is dialled in milligrams. A compounded pen is dialled in clicks, and a click is a volume, not a dose. The same click delivers a different amount in every pen, because it depends entirely on how much peptide went into that cartridge. Work it out per pen, every pen.
Cost per mg is the only figure that compares two suppliers honestly. Vial price does not, because vial strengths differ.
What this is and is not. It plots how much is still present when the next dose arrives. Inject far apart relative to the half-life and there is no build-up, so every dose acts alone. Inject close together and levels climb until clearance matches input, then hold. It says nothing about effect or tolerance, and it is only as good as the half-life you entered.
These calculators run arithmetic on numbers you provide. They hold no dosing recommendations, no protocols and no cycle lengths. What you type stays in your browser and is never sent anywhere.
How the reconstitution maths works
There are only two steps, and the calculator above is doing both of them.
First, the concentration. Divide the peptide in the vial by the water you add. A 5mg vial with 2mL of bacteriostatic water gives 2.5mg per mL, or 2 500mcg per mL.
Second, the volume. Divide your dose by that concentration. A 250mcg dose out of a 2 500mcg/mL solution is 0.1mL. On a U-100 insulin syringe one millilitre is 100 units, so 0.1mL is the 10 unit mark.
The single most common error in this process has nothing to do with the arithmetic: it is mixing up milligrams and micrograms. 1mg is 1 000mcg. A tenfold slip here is a tenfold slip in what ends up in the syringe.
Choosing how much water to add
The volume of water is your choice, and it changes nothing about how much peptide you have. It only changes where the dose falls on the syringe.
A weaker solution, so each dose occupies more volume and lands on a larger, easier-to-read mark. Useful when a dose would otherwise sit below two units.
A stronger solution and a smaller draw. Harder to measure accurately, but it keeps the total volume within what the vial can physically hold.
A practical target is to land your usual dose somewhere between 10 and 50 units, where the markings are easy to read without a magnifier. The How much water? mode works backwards from exactly that: pick the mark you want, and it tells you what to add.
Before you mix
- Use bacteriostatic water, not sterile water, if the vial will be used more than once. Sterile water contains no preservative.
- Let a cold vial come to room temperature first.
- Run the water slowly down the inside wall of the vial rather than firing it straight into the powder.
- Swirl gently until dissolved. Do not shake.
- Do not use it if the solution stays cloudy, changes colour, or holds visible particles.
After mixing
Once reconstituted, a peptide is generally treated as having a working life of about 28 days refrigerated, which is why the calculator flags a vial that would take longer than that to finish. Write the date on the vial when you mix it. If the arithmetic says a vial lasts four months, mix less at a time.
Why a pen click is not a dose
This one catches people out constantly. A branded pen is dialled in milligrams, so a number on the dial means the same thing every time. A compounded pen is dialled in clicks, and a click is a volume, not a dose.
What a single click delivers depends entirely on how much peptide went into that particular cartridge. Two pens that look identical can deliver very different amounts per click. The pen calculator exists for exactly this reason: work it out per pen, for every pen, rather than carrying a number across from the last one.
These calculators are provided for educational purposes and perform arithmetic only. They are not medical advice, do not recommend any dose, protocol or cycle length, and are not instructions for any product sold on this site. Always consult a qualified healthcare professional about your own circumstances.
New to this? Our step-by-step reconstitution guide explains how to mix a vial and how to choose the volume of water.