Intermittent Fasting Schedule Planner
Turn your wake time into a simple fasting clock
Intermittent fasting windows and common questions
What does a 16:8 or 18:6 schedule actually mean?
Time-restricted intermittent fasting usually means you eat within a daily window and fast the rest of the time. A 16:8 pattern means fasting for about 16 hours and eating in an 8-hour span each day; 18:6 means 18 hours fasting and a 6-hour eating window. Many people use these as simple, repeatable daily rhythms rather than strict “diets”.
Does this planner tell me if intermittent fasting is safe for me?
No. This page is a timing planner only. It helps you see where a fasting and eating window might sit between your own wake and sleep times. Safety, benefits and risks depend on your health history, medicines, work pattern, and more. For that, you need individual advice from a doctor or registered dietitian, not a generic tool.
Who should be extra careful or avoid fasting schedules?
People who are pregnant or breastfeeding, have a history of eating disorders, take medicines that rely on regular meals, or live with conditions such as diabetes or cardiovascular disease often need tighter medical supervision. Some may be advised not to fast at all. If you fall into any medical or higher-risk group, speak with your care team first.
How do I choose between 14:10, 16:8, 18:6 or 20:4?
Many beginners try moderate eating windows such as 14:10 or 16:8 after getting a green light from a clinician. Tighter schedules like 18:6 or 20:4 can feel demanding and may not be sustainable or appropriate for everyone. The right pattern depends on your health, work, training and family life, not just willpower.
Can I slide the eating window earlier or later than the suggestion?
Yes. The planner centers the eating window between your wake and sleep times so you get a balanced daytime block. In real life you might shift that window earlier or later to match commute, workouts, or family meals. Think of the output as a starting point to tweak, not a strict rule.
What if my wake and sleep times change a lot?
If you work rotating shifts or have very irregular nights, a fixed daily fasting window can be harder to keep. You can still use the tool to test different wake and sleep times, but you might be better off discussing timing with a clinician who understands your schedule and circadian rhythm challenges.
Does the planner say what to eat during the eating window?
No. It ignores calories and food types and simply helps you see the clock. Most medical and nutrition groups still emphasise overall diet quality, balanced meals and sustainable habits over any one timing pattern. You can combine the timing you choose here with whatever eating pattern your healthcare team recommends.
How to use this intermittent fasting schedule planner
This page is built to do one job: take a fasting pattern you already have in mind and line it up with your usual wake and sleep times so the fasting and eating windows feel realistic.
1. Decide on a pattern with your care team if needed
Before you change when you eat, check whether intermittent fasting is appropriate for your situation, especially if you have medical conditions or take regular medicines. Once you have a plan or at least a pattern you want to test, choose it from the drop-down list (for example, 16:8, 14:10 or 18:6).
2. Enter your typical wake and sleep times
Add the time you usually wake up and when you usually go to sleep on a normal day. The calculator assumes you wake once and sleep once in a 24-hour period and that your main awake time sits between those entries. If your days vary, use a “most common” pattern as a base and adjust later.
3. Optional: Tag the plan with a short note
The note field lets you label the plan with something like “office days”, “night-shift week” or “training block”. That label is included in the copyable summary so you can keep several different patterns straight in your notes.
4. Read your eating and fasting windows
When you hit Build fasting day plan, the result shows:
- Your chosen fasting pattern (for example, 16:8).
- An eating window in 24-hour time, such as 11:00–19:00.
- A fasting window covering the remaining hours.
- A small table that lines up wake, eating start, eating end and sleep.
The tool keeps the eating window inside your wake–sleep span and centers it so meals land in the middle of your day, where many people find it easiest to eat enough.
5. Tweak around the suggestion and copy your summary
Treat the output as a starting template. You might move the window earlier toward breakfast on early work days or later on social evenings, as long as you keep the total fasting and eating hours similar. Use the Copy summary button to drop the plan into your calendar, notes app, or a message to your coach or care team.
Remember that this planner only handles timing. It does not claim that fasting will help you or that it is better than other eating patterns for your health. Those decisions should always be made with proper medical and nutrition advice that takes your own risks and preferences into account.
How the intermittent fasting timing math works
The math behind the planner is deliberately simple. It turns your selected fasting pattern into hours, uses your wake and sleep times to define a day, and then fits the eating window neatly inside that block.
1. Convert your chosen pattern into hours
Each option has a fixed split between fasting and eating. For example, 16:8 means a 16-hour fasting window and an 8-hour eating window. The planner stores those as simple numbers of hours.
2. Turn your wake and sleep times into minutes
Your wake and sleep times are converted into minutes from midnight (for example, 07:00 becomes 420, 23:00 becomes 1380). The planner assumes your sleep time falls after your wake time on the same calendar day, so it will ask you to adjust if you enter times that do not make sense together.
3. Fit the eating window between wake and sleep
The tool calculates how many minutes you are typically awake and then centers the eating window inside that span. In simple terms:
Eating start = Wake + (Awake span − Eating hours) ÷ 2
Eating end = Eating start + Eating hours
This keeps the main meals away from both the moment you wake up and the moment you go to bed, leaving some buffer on each side.
4. Define the fasting window around the eating block
Once the eating window is fixed, the fasting window simply covers the rest of the 24-hour day. If your eating window runs from 11:00 to 19:00, your fasting window is 19:00–11:00. Times that cross midnight are still shown in 24-hour clock format so they are easy to read.
This approach does not try to model hormones, circadian biology or disease risk. It just gives you a clean, repeatable day outline that you and your clinicians can adjust or ignore depending on whether intermittent fasting really makes sense for you.
References and further reading on intermittent fasting
These resources discuss intermittent fasting patterns, potential benefits and risks, and who should seek extra medical advice:
- Johns Hopkins Medicine — Intermittent fasting: what is it and how does it work? — explains common time-restricted schedules such as 16:8 and stresses checking with a doctor before starting.
- NIH News in Health — To fast or not to fast — overviews fasting styles, including daily time-restricted eating, and highlights that intermittent fasting is not right for everyone.
- Cleveland Clinic — Intermittent fasting: 4 different types explained — describes popular schedules like 16/8 and 14/10, who might try them and why medical guidance matters.
Use these as background reading and combine them with personalised guidance from your own healthcare professionals or registered dietitian before committing to any new fasting routine.