Work backward from the dose you want. Enter your vial, your target dose, and how many units you want to draw, and get the exact bacteriostatic water to add so the dose lands on a clean syringe mark.
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PepWiseTip: vials are physical glass vials, usually 3 mL or 5 mL. You can’t add more bacteriostatic water than the vial holds, so very small doses at very high units may not fit.
A normal reconstitution calculator starts from the water you add. This one starts from the result you want. You choose the dose and how many units it should read on the syringe, and it solves for the water. The formula is water to add (mL) = vial (mg) × draw volume (mL) × 1000 ÷ dose (mcg), where draw volume = units ÷ 100 on a U-100 insulin syringe.
You have a 5 mg vial and you want a 250 mcg dose to read as a clean 20 units. Draw volume is 20 ÷ 100 = 0.20 mL. Water to add is 5 × 0.20 × 1000 ÷ 250 = 4 mL. That makes 1.25 mg/mL, so 250 mcg is 0.20 mL = 20 units, and the vial holds 20 full doses (5 mg ÷ 250 mcg).
Doses per vial depend only on the total drug and your dose, not on the water: doses = vial (mg) × 1000 ÷ dose (mcg). A 5 mg vial at 250 mcg is 20 doses; at 500 mcg it is 10. The calculator shows this so you know how long a vial lasts and when to reorder.
Reading 20 units on a U-100 syringe is far easier and more accurate than eyeballing an odd mark like 13.5. Picking your units first, then setting the water to match, removes the guesswork and makes every dose repeatable.
PepWise stores your vial size, water, and target for every peptide and does this math for you on each dose, then logs the injection site and how you feel over time. It is free to start on iPhone, Android, and web.
Work backward from how you want to draw the dose. Water to add (mL) equals the vial amount (mg) times the draw volume (mL) times 1000, divided by the dose (mcg), where draw volume equals your desired units divided by 100. A 5 mg vial dosed at 250 mcg as 20 units needs 4 mL of water.
A normal reconstitution calculator starts from the water you add and tells you the dose volume. A reverse calculator starts from the dose you want and the units you want to draw, and tells you how much bacteriostatic water to add.
Yes. Pick a round, easy-to-read number of units on your U-100 syringe, such as 10 or 20, and the calculator sets the water so your dose lands exactly on that mark.
Peptide vials cannot hold more water than their capacity. If the result exceeds your vial, draw more units per dose or use a larger vial. The calculator warns you when this happens.
Doses per vial equal the vial amount (mg) times 1000, divided by the dose (mcg). It depends only on the total drug and your dose, not on the water. A 5 mg vial at 250 mcg is 20 doses; at 500 mcg it is 10.
PepWise is an informational and educational tracking tool, not medical advice and not a medical device. Peptides may be experimental or restricted; consult a licensed healthcare provider before starting, changing, or stopping any protocol. Operated by STC Consulting, Inc.