For peptides, GLP-1s, and anything else that comes in a vial
Stop doing vial math
in your head.
You bought a 10 mg vial. You want 2.5 mg twice a week. How much bac water, how many units on the syringe, and how long until you need to reorder? Vialkeeper answers all four, then keeps the answer as you use the vial up.
Free to use, no card required. An email and a password is all you need. Or work out a dose in the calculator without signing up at all.
Semaglutide
10 mg vial · 2 mL bac water · SubQ
Draw
25units
Dose
1.25mg
Left
6.2mg
Everyone starts with the notes app.
Then it's a photo of a handwritten conversion chart, a calculator app, and a screenshot of a reddit comment you're fairly sure was right. The chart assumed a 5 mg vial and you have a 10. The concentration changed when you added more water than you meant to. Somewhere in there you stopped being certain how many doses were left in the vial sitting in your fridge.
None of that is hard math. It's just math you're doing at 6 in the morning, half awake, holding a syringe — which is exactly when a decimal point goes missing.
Vialkeeper works it out once, writes it down, and updates it every time you log a dose.
Reconstitution
It works in both directions
Most calculators only go one way: you tell them how much water you added, they tell you how much to draw. That's fine until the answer is 17.5 units and you're squinting at a syringe trying to split a tick mark.
Vialkeeper also goes backwards. Tell it you want your dose to land on a clean 20 units and it tells you exactly how much bacteriostatic water to add before you mix. If that amount won't physically fit in the vial, it says so instead of handing you a number you can't use.
Every formula it uses is written out on the methodology page, so you can check the math yourself.
10 mg vial, 1.25 mg per dose, drawn to a round 25 units.
Inventory
Your vials count themselves down
Add the vials you have. Every dose you log gets pulled out of the oldest one first, and when it runs dry the remainder comes out of the next — the same way you'd use them.
So the number on screen is what's in the fridge. You get milligrams remaining, doses remaining, the date you run out, and a reorder-by date that works backwards from however long your supplier usually takes.
Schedule
Real schedules, not just daily
Pick the actual days you inject — Monday and Thursday, weekends only, whatever your protocol is. Reminders follow those days instead of nagging you seven times a week and training you to ignore them.
Reminders wait for you in the app, and if you switch them on they arrive as a notification on your phone or laptop. That's a browser notification, not a text message.
M
T
W
T
F
S
S
Thursday 8:00 AM · Semaglutide, 25 units
Twice a week, on the days you inject.
History
A record you can show someone
Every dose is logged with the date, the amount, and the injection site, so you can rotate sites properly instead of relying on memory.
Over time that turns into something useful: how consistent you've been, what your weekly total really is, and a clean history to bring to an appointment — as a printable PDF report if you'd rather hand someone a page than a phone.
Privacy
We ask for as little as possible
An email and a password gets you an account. That's the only personal detail we ask for — no phone number, no address, no ID. Your log is yours; it isn't shown to other users and it isn't for sale.
And to be plain about what this is: Vialkeeper is a notebook that does the math. It doesn't recommend compounds, doses, or protocols, and it's no substitute for talking to a clinician.
Pricing
Free to start, and free to stay
Nothing counts down from the day you sign up, and there's no card to enter. The free plan is a real plan — and there's one free week of Pro sitting on every account, to claim whenever you want to see what it adds.
Free
$0forever
Enough to run a single prescription properly, for as long as you want to.
- The reconstitution calculator, both directions
- Up to 2 medications
- Unlimited dose logging
- Weight tracking with a goal line
- The last 14 days of your dose history
- Export everything you've logged, on any plan
Pro
$5.99USD / month
or $39.99 a year — about $3.33 a month, billed once.
Everything in Free, plus
- Unlimited medications
- Your complete dose history, not just the last 14 days
- Dose reminders only on your scheduled days
- Vial inventory with oldest-first depletion and reorder warnings
- Cycles, dose ladders and tapers
- Estimated level charts from the half-life you enter
Start free and upgrade from inside the app whenever Pro is worth it to you. Cancel any time, with no notice period — you drop back to the free plan, and nothing you have logged is ever deleted for not paying.
Card, Apple Pay or Google Pay, handled by Stripe. We never see your card details.
Questions people ask
Yes. Every account has one free week of Pro on it, and you claim it from inside the app whenever you like rather than the day you sign up. No card, so there's nothing to cancel. When the week is up you land back on the free plan.
Your account drops to the free plan — it doesn't lock. You keep the dose calculator, up to two medications, unlimited dose logging, weight tracking and the last 14 days of history. Reminders, vial inventory, cycles and your full history go back behind Pro, but nothing you logged is ever deleted, and you can export all of it on any plan.
Whatever you enter. There is no fixed list to choose from — you name the medication yourself, so anything that comes in a vial, a pen or a bottle can go in. It covers three kinds: vials you reconstitute yourself, pre-mixed liquids, and oral doses.
Any time, on any plan, including free. A PDF report of your doses and weights made to print or hand to a clinician, your doses and weights as CSV for a spreadsheet, and the whole account as JSON if you want the raw thing. No export is behind the paywall.
It goes immediately, and it does not come back. Deleting cancels your subscription first — if that step fails nothing is removed, so you can never end up deleted but still billed — and then clears your doses, medications, vials, reminders, dose ladders, weights and any devices you had switched notifications on for. There is no recovery window, so export anything you want to keep before you confirm.
For reading, yes. The app keeps a copy of your medications, today's doses and your recent history on the device, so it opens and shows your numbers on a plane or in a basement. Saving a new dose needs a connection.
Vialkeeper runs in any browser and installs to your home screen like an app, on both iPhone and Android. There is also an Android build you can download and install directly, with the Play Store version on its way. On iPhone the browser version is it for now.
No — we don't ask for one. Reminders appear in the app, or as a browser notification if you switch them on, rather than as text messages.
Enter the water you added and it works forward from there — how much to draw, what's in each dose, how many doses are left. The reverse calculation is for vials you haven't mixed yet.
Both, plus mL, IU and tablets. Doses in mcg or mg get converted automatically when they're drawn out of your inventory.
Inventory is recalculated from your whole dose history rather than counted down blindly, so a back-dated entry or a deleted one puts the vial levels right again.
No, and it isn't trying to be. It records what you tell it and does the math. Every number should be confirmed against your syringe and your prescriber.
Every vial, every dose, kept.
Set up your first medication in about two minutes. The calculator is right there on the first screen if you just want to check a number.
Works in any browser and installs to your home screen. There's also an Android beta if you'd rather have the real app — the Play Store version is on its way.