Intermittent fasting calculator
Pick a schedule and see your eating window, your fast, and a live countdown to whatever comes next.
Times shown in your device's timezone: —
Your day
| Eating window | — – — |
|---|---|
| Fast | — – — |
Your week
5:2 runs on a weekly rhythm, so there's no daily countdown. Keep the two low-calorie days apart, and try to line them up with rest days.
About this schedule
The most popular daily schedule — a 16-hour fast with an 8-hour eating window. Most people find it sustainable long-term.
A tighter 6-hour window. A reasonable step up once 16:8 feels comfortable.
Also called the Warrior pattern — a 4-hour window. Plan meals so you still hit your protein and calorie targets.
A gentler 10-hour window — a good starting point if you're new to fasting.
One meal a day — a 23-hour fast. It takes planning to fit a full day's nutrition into one sitting, and it doesn't suit everyone.
Five days of normal eating and two non-consecutive days at about 500 kcal. It's a weekly rhythm rather than a daily window.
Fasting isn't suitable for everyone. If you're pregnant, or have a history of disordered eating, talk to a clinician before starting.
How this is calculated
Each daily schedule is a fixed split of the 24-hour day into a fast and an eating window. Your window start sets where the eating period begins; the fast fills the rest of the day.
The countdown compares the current time on your device to your window. Times are formatted in your device's locale and timezone — nothing is sent anywhere. 5:2 is weekly, so it shows a week strip instead of a countdown.
Estimates only. Not medical advice. Talk to a clinician for personal guidance.