How to use the Reconstitution Calculator

From the Home tab, tap the Reconstitution Calculator tile in the tool grid. The screen is one scrollable form: four questions from top to bottom, with the answer updating live at the bottom as you tap. There is no “calculate” button — every change recalculates instantly.

The calculator assumes a reconstituted vial — powder already mixed with bacteriostatic water. If your vial is still dry, mix it first:

• •Let the vial reach room temperature; swab both stoppers with alcohol.
• •Draw your chosen amount of bacteriostatic water (you'll enter this exact number in Step 3).
• •Inject it slowly down the inside wall of the vial — not straight onto the powder.
• •Swirl gently until clear. Never shake.
• •Label the vial with today's date and the water amount you used.

The first control is a stack of three cards, one per insulin-syringe size. Tap the one that matches the syringe in your hand — the selected card highlights in blue.

Each card shows the size two ways, because syringes are labeled two ways: milliliters (0.3 / 0.5 / 1.0 ml) and units (30 / 50 / 100). They're the same thing — insulin syringes mark 100 units per milliliter. The little illustration on each card mirrors the real barrel: the 0.3 ml syringe is numbered every 5 units, the 0.5 ml every 10, the 1.0 ml every 20.

This is the number printed on your vial's label — the total milligrams of peptide it contained as powder. Tap a preset chip, or tap Other to type any amount (decimals are fine).

Tapping Other reveals a numeric field right below the chips:

Use the total in the vial, not your dose — a “5 mg vial” means 5 mg of peptide before any water was added. This number never changes for the life of the vial.

Enter the amount of bacteriostatic water you mixed into the vial (or plan to). Same pattern: preset chips or Other for a custom amount.

This is the control people misunderstand most, so it's worth being precise: water sets the concentration, nothing else. More water spreads the same peptide across more volume, so every dose becomes a longer pull; less water makes every dose a shorter pull. The peptide per dose is identical either way.

Your per-injection dose. Two controls live here: the mcg / mg toggle on the right of the question, and the preset chips below it.

The toggle switches the unit your dose is written in. Protocols are quoted both ways — 250 mcg and 0.25 mg are the same dose — so enter whichever form yours uses and skip the mental conversion. Flipping the toggle swaps the presets to match:

Note that switching units resets the dose selection to the first preset — the old chips would mean something different in the new unit, so the app makes you choose again rather than silently converting. As everywhere else, Other opens a field for any custom amount.

The answer card sits below the four questions and updates with every tap. It has three parts:

• •The sentence is the instruction: pull the plunger until the stopper sits at that unit mark. It's rounded to one decimal — “7.5 units” means halfway between 7 and 8.
• •The ruler draws your selected syringe with the blue marker at the exact draw point, so you can match the picture against the real barrel in your hand.
• •The stats line gives the same answer three more ways: mL (the draw as a volume), concentration (what one milliliter of your mixed vial contains — worth writing on the vial label), and doses per vial (how many injections this vial yields at this dose — your reorder early-warning).

Until all four questions have valid answers, the card shows a prompt instead: “Pick a vial amount, water volume, and dose to see how far to pull the syringe.”

If one dose is a bigger volume than your selected syringe holds, the result card adds an amber warning:

The warning always names your two ways out:

• •Pick a larger syringe — tap a bigger card in Step 1. The example above (50 units) fits comfortably in a 0.5 or 1.0 ml syringe.
• •Use less water — if the vial isn't mixed yet, a smaller water amount concentrates the vial so the same dose becomes a shorter pull. (Once mixed, the concentration is locked in for that vial.)

On a 1.0 ml syringe — already the largest — the warning suggests using less water or splitting the dose into two injections instead.

The third row exactly fills a 0.3 ml syringe — legal, but with zero headroom. That's a case where tapping the 0.5 ml card in Step 1 makes the draw easier to handle.

That's the entire calculation — three divisions and a multiply. The value of the calculator isn't that the math is hard; it's that it's done identically every single time, with the syringe fit checked and the answer drawn where you can compare it against the barrel.

• •My dose presets changed when I tapped mg. By design — presets match the active unit (50/100/250/500 for mcg; 0.5/1/2/5 for mg), and the selection resets to the first preset so you never carry a stale value across units.
• •The result is a decimal, like 7.5 units. Perfectly valid — the ruler marker sits halfway between marks. If you'd rather land on a whole number, adjust the water amount before mixing your next vial.
• •My vial/water/dose isn't a preset. Every question has an Other chip that opens a numeric field. Decimals like 7.5 mg or 2.5 ml are fine.
• •Does changing the syringe change my dose? No. Steps 2–4 determine the dose and volume; Step 1 only changes how the ruler is drawn and whether the overflow warning fires.
• •My vial is already mixed — can I still use this? Yes. Enter the water amount you actually used when you mixed it (this is why the label step matters), and the answer is exact.
• •Does the calculator save my numbers? No — it opens fresh each time. Write the concentration and “pull to X units” on the vial label so the answer travels with the vial.

New to reconstitution itself? The five-minute primer is at Reconstitution basics, and the app-setup walkthrough is in Getting started with peptides.