What the curve gives you
EstimatedWorked example: tirzepatide 5 mg weekly, half-life 120 h. Milligrams still in the body. Dashed is projected from the schedule.
6.1mg
Now
6.5
Peak
3.5
Trough
5.1
Average
Every dose, every level, one protocol
Peptain logs peptide and GLP-1 doses in seconds, estimates what is still circulating from each compound's half-life, and keeps sites, cycles, nutrition and body scans in the same place.
Free to download. No account needed.
PK estimator
An estimate you can reason about
Peptain models what is still circulating from the doses you have logged and each compound's published half-life and time to peak. Switch between 12 hours, a day, a week, a month. It is arithmetic on your own log, which is exactly what makes it useful and exactly why it is not a measurement.
What it does not
Measure a level
Absorption, body composition and the site all move the real number. Only bloodwork tells you what is in you.
Recommend a dose
The ranges in the catalog are reference figures from published literature, not a suggestion for you.
Diagnose anything
Peptain is a tracking tool. It has no opinion on whether a protocol is right, and it is not a medical device.
Talk to your doctor before starting, changing or stopping anything.
One tap when you take it, and the rest keeps itself
- Dose logging
- Tap, pick the compound, done. Dose, time and site recorded, and the vial drawn down so you know what is left before you run out.
- Schedules and stacks
- Group compounds into a named protocol and give each its own frequency: daily, weekly, or every third day. Peptain works out what is due when.
- Site rotation
- A body map colour-codes every injection site by how recently it was used, across all your compounds, and points at the one that has rested longest.
- Cycles
- On and off periods on a calendar. See which day of a cycle you are on, when the next phase starts, and how compounds overlap.
- Reminders
- A quiet notification at the time you set, per schedule. Nothing else pushes at you.
- The catalog
- 98 compounds across GLP-1, peptides, TRT, supplements and vitamins, each with half-life, typical dose ranges, mechanism and references.
All of that is free, and none of it needs an account. Guest mode logs to the device and stays there.
Built to be opened at 7am, half awake
Everything you touch daily is one tap from the home screen: what you last took, what is due, what is still in you, and how much is left in the vial.
Peptain Plus
Photographs, instead of trying to remember
A protocol changes you slowly enough that you cannot see it happening. The scans give you something to compare against: the same photo, the same read-out, week after week. Every scan is kept so you can scroll back to where you started.
Body scan
One photo, and an estimate of composition, muscle groups, symmetry and posture, tracked over time.
Face scan
Skin condition, hydration and puffiness: the changes people notice first and describe worst.
Free does the tracking. Plus does the analysis.
Nothing in the free app is taken away or time-limited. Plus adds the work that needs a model behind it, and one subscription covers all of it.
- AI body scan: composition, muscle groups, symmetry, posture
- AI face scan: skin, hydration, puffiness over time
- Food scanner: photograph a meal for calories and macros
- Bloodwork logging against 38 markers
- Side effect and mood tracking
- Daily insights across protocol, nutrition and how you feel
The scans are the one place data leaves the phone: the photo is sent to be processed, and the app says so before it does it. Nothing is used to train anything, nothing is sold, and there are no ads.
Compound catalog
The full reference98 compounds, with the numbers attached
GLP-1 medications, peptides, TRT esters, supplements and vitamins. Each one carries its half-life, typical dose range, mechanism and the references behind them, which is also what lets the level estimate work the moment you log a dose rather than after you have configured anything.
How to run the tracking side of a protocol
All guidesHow to track a GLP-1 protocol properly
A weekly injection is easy to take and surprisingly easy to lose track of. What to record, why the date matters more than the dose, and how to keep a titration legible to the person who prescribed it.
Ozempic, Wegovy, Mounjaro, Zepbound: which is which
Four brand names, two molecules, and a lot of confusion. What each name actually refers to, why the same drug is sold twice under different labels, and what that means when you are keeping a record.
Peptide half-life, explained
Half-life is the number that decides how often something is injected, how long it takes to settle, and how long it lingers after you stop. Here is what it does tell you, and the three things people assume it tells them that it does not.
mg, mcg and units: the arithmetic people get wrong
Most dosing errors in this space are not judgement calls, they are unit conversions. What a "unit" on a syringe measures, how concentration turns milligrams into a mark on a barrel, and why your log should hold both.
Questions worth asking first
Can Peptain track Ozempic, Mounjaro, Wegovy or Zepbound?
Yes. Semaglutide, tirzepatide, liraglutide, retatrutide, dulaglutide and the rest of the GLP-1 class are in the compound catalog with their half-lives and typical dose ranges already filled in, so a log takes one tap and the level estimate works from the first dose. Brand or generic, it is the same molecule to the app.
Does Peptain tell me what to take, or how much?
No. Peptain records the protocol you and your doctor have decided on and shows you what you have actually done with it. It never suggests a compound, never proposes a dose and never adjusts one, and the dose ranges in the catalog are reference figures from published literature, not a recommendation for you.
What is the PK estimator actually estimating?
It plots how much of a compound is still likely to be circulating, from the doses you have logged and that compound's published half-life and time to peak. It is arithmetic on your own log: a model, not a measurement. Absorption, body composition and injection site all move the real number, so treat the curve as a shape to reason about rather than a reading. Only bloodwork tells you a level.
Is Peptain free?
The tracking is. Dose logging, schedules and stacks, cycles, reminders, injection site rotation, the PK estimator, the compound catalog and weight logging are all free with no account. Plus adds the analysis: AI body and face scans, the food scanner, bloodwork and side effect logging, the mood board, and daily insights.
Where does my health data live?
On your device. Guest mode works with no account at all, and nothing you log leaves the phone unless you turn on cloud sync. The AI features are the exception and the app says so before you use one: a body, face or food photo is sent for processing and is not used to train anything. No ads, and no selling data to anyone.
Can I run several compounds on different schedules at once?
That is what stacks are for. Group compounds into a named protocol such as Morning Stack, give each one its own frequency, daily or weekly or every third day, and Peptain works out what is due when. On and off cycles sit on the same calendar, so you can see which day of a cycle you are on and when the next phase starts.
How does injection site rotation work?
Every logged dose records where it went. The body map then colour-codes each site by how recently it was used and points you at the one that has rested longest, across every compound you run rather than one at a time.
Is Peptain on Android?
Yes, on both the App Store and Google Play, with the same features on each. The app is translated into 24 languages.
Consistency is the whole protocol. Peptain is how you keep it.
Free on iOS and Android, in 24 languages.