Intermittent fasting is a way of organizing when you eat. It alternates a period without food with a period in which meals are eaten. It is not a single meal plan, and choosing a schedule does not tell you what or how much to eat.
The most useful starting point is understanding the notation. A daily schedule such as 14:10 describes fourteen fasting hours followed by a ten-hour eating window. Both numbers refer to time, not calories, and add up to twenty-four hours.
How daily fasting schedules are written
| Schedule | Fasting window | Eating window |
|---|---|---|
| 12:12 | 12 hours | 12 hours |
| 14:10 | 14 hours | 10 hours |
| 16:8 | 16 hours | 8 hours |
These are examples of how time is divided, not recommendations for a particular person. An eating window is the period in which you schedule meals; it does not mean eating continuously for the whole window.
What counts as the start of your timer?
For a simple daily schedule, enter the time you finish your last meal. The calculator adds the fasting duration to that time. If the result crosses midnight, the next eating window starts the following day.
For example, finishing a meal at 8:00 PM and adding twelve hours gives 8:00 AM the next day. Adding fourteen hours gives 10:00 AM. Adding sixteen hours gives noon. The arithmetic is the same even when your preferred meal times are different.
Plan around your real calendar
Consider the commitments already in your day: work hours, travel, exercise, shared meals and any medication instructions. A schedule should be considered in that context. Do not change prescribed medication timing or food requirements to fit an app timer.
A written example can be useful before starting anything. Record a typical last-meal time and compare the example schedules with the next day’s commitments. If a window does not fit, that is useful information to discuss with a qualified professional.
What an intermittent fasting app can track
A fasting tracker records time. A history view can help you see patterns in recorded fasts, while water logging and body measurements provide separate observations. Those records do not diagnose a condition or prove that a schedule is improving your health.
Use notes to distinguish your planned schedule from what actually happened. A changed appointment, a late meal or a day without tracking should be recorded honestly. The value of a log is that it reflects your routine, rather than a target you wish you had met.
Common misunderstandings
- A longer fasting window is not automatically a better choice.
- An app timer is not a medical recommendation.
- The schedule alone does not guarantee weight loss or other health outcomes.
- Sleep, food choices and medical needs still matter outside the timer.
Discuss changes with a clinician. Johns Hopkins advises against fasting for under-18s, people who are pregnant or breastfeeding, people with eating-disorder histories, and people with type 1 diabetes who use insulin. This tool cannot assess medical suitability.
Explore an example before choosing a routine
Use the fasting schedule calculator to understand the arithmetic, or read the 16:8 fasting guide for a worked example.
Health information source: Johns Hopkins Medicine’s intermittent fasting overview. This page is educational and is not personalized medical advice. Published October 13, 2026 by the Fasting+ team.