Free tool · no signup
Enter what's left in the vial, your dose, and how often you dose. Get a projected run-out date back — and a reorder-by date if you tell it your lead time. Nothing to install, no account, no compound list to pick from.
Blend? Enter the vial size and the dose the same way: both for one component, or both as totals.
Whole days. 1 for daily, 7 for weekly, and so on.
How many days ahead your supplier needs. Leave blank to skip the reorder-by date.
Starting from today, the calculator walks forward one day at a time at the frequency you entered, subtracting your dose from what's remaining on every day it's due, and reports the day the vial runs out — the same engine VialMath itself uses for every vial on record, not a separate estimate. Doses remaining is the vial amount divided by your dose, full doses only. The reorder-by date, if you gave a lead time, is simply the run-out date moved back by that many days.
You have 6 mg remaining. Your dose is 0.5 mg, taken every 3 days. Doses remaining: 6 mg ÷ 0.5 mg = 12. Counting forward from today every 3 days, the 12th dose lands 3 × 11 days out — 33 days from today. With a 5-day reorder lead time, the reorder-by date is 33 − 5 = 28 days from today. Every number above is checkable on a calculator.
VialMath keeps your calculations, schedule, inventory and history connected.
More free tools: the reconstitution calculator, how long will a vial last?, and the full list →
Divide what's left by your dose to get doses remaining, then space those doses out at your dosing frequency, starting today. The calculator above does that day-by-day rather than as a single average, so it stays exact even when the amount left isn't a clean multiple of the dose.
The run-out date, moved earlier by however many days your supplier needs to get you a new vial — so the reorder happens before the old one is empty, not after.
No — it projects forward from the amount you enter today, assuming every scheduled dose from here is taken on time. A missed or extra dose changes how much is actually left; re-enter the current amount and the projection updates.
This free tool assumes one steady "every N days" cadence. On/off cycles, weekday-only schedules, and more than one dose a day are handled in the full VialMath app, which already runs this exact projection against a real schedule.
Not in the full app. Log a dose once and the run-out date and reorder-by date recompute on their own — nothing to re-enter by hand.
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Your address, the page you signed up on, and the date — nothing else is kept with it. Never sold, never shared, never passed to anyone selling anything. One click unsubscribes. Your protocol data is separate and stays on your device — the app has no account and sends us nothing.