The 16:8 schedule
16:8 is the most common way people organize their eating around a fasting window. Here's exactly what it means and how to keep track of it without thinking about it.
What 16:8 means
The numbers describe two blocks of time that add up to 24 hours. 16 hours is the time you're not eating, and 8 hours is your eating window, the stretch of the day when meals are on the table. Outside that 8 hour window, you're fasting; inside it, you're not.
It's a routine, not a rulebook. You choose when your 8 hour window starts, and the App does the arithmetic for the other 16 hours automatically.
How the timer helps
The part people actually get wrong isn't the concept, it's the clock. Once you're a few hours into a fast, "did I start at 8 or 8:30" gets fuzzy, and mental math about when a window opens gets old fast. WhenCanIEat starts a countdown the moment you begin your fast and flips to a live count-up once your window opens, so the answer to "when can I eat" is always just one glance away, no math required.
An example day
Here's what a 16:8 schedule might look like if your eating window runs from noon to 8:00 PM:
| Time | What's happening |
|---|---|
| 8:00 PM (previous day) | Eating window closes, fast begins |
| Overnight | Fast continues through sleep |
| 8:00 AM | Timer shows the countdown to your window opening |
| 12:00 PM | 16 hour fast complete, eating window opens |
| 12:00 PM to 8:00 PM | Eating window is open |
| 8:00 PM | Window closes, next fast begins, streak updates |
Your own window can start and end whenever fits your day, this is just one example. Some people run mornings-open instead, starting their window at 7:00 AM and closing it at 3:00 PM.
Why people pick 16:8 first
It fits around a typical day without much rearranging: skip or shrink one meal, keep the other two roughly where they already are. It's also a schedule you can start and stop as your routine changes, week to week, with nothing to reconfigure beyond picking the preset.
Getting started
Open WhenCanIEat, choose the 16:8 preset, set your window start time, and start your first fast. Free to try, no account needed.
Start your 16:8 timer
All presets are included in your free trial, first 2 fasts on us. Subscribe only if you want to keep going after that.