What Is an Intermittent Fasting Timer?
An intermittent fasting timer tracks how long you have gone without eating so you always know where you stand in your fasting window. Instead of guessing, you start the timer when you finish your last meal and it counts up in real time toward your goal — 16 hours for 16:8, 18 for 18:6, and so on. This free fasting timer also shows a progress bar toward your goal and lights up stage markers as your body moves from digestion into fat burning, ketosis and autophagy. Your start time is saved in your browser, so you can refresh or close the tab and your fast keeps running.
Fasting Windows Explained (16:8, 18:6, 20:4, OMAD)
Intermittent fasting splits your day into a fasting window when you only drink water, black coffee or tea, and an eating window when you have your meals. The numbers tell you how those hours are divided:
- 14:10 - a 14 hour fast with a 10 hour eating window. A gentle starting point.
- 16:8 - a 16 hour fast with an 8 hour eating window. The most popular protocol and the default here.
- 18:6 - an 18 hour fast with a 6 hour eating window. A step up once 16:8 feels easy.
- 20:4 - a 20 hour fast with a 4 hour eating window, also called the Warrior Diet.
- OMAD (23:1) - One Meal A Day: a 23 hour fast with a single one hour eating window.
You can also set a custom goal in hours if your fasting window does not match a standard split.
What Happens in Your Body While Fasting
As the hours pass, your body shifts through several stages. This fasting timer lights up each marker as you reach it:
- ~4 hours - Food digested. Your last meal has moved through the stomach and blood sugar and insulin start to settle.
- ~12 hours - Fat burning begins. With glycogen stores running low, your body turns increasingly to stored fat for fuel.
- ~16 hours - Ketosis. The liver ramps up ketone production, giving your brain and muscles an alternative energy source.
- ~18 hours - Autophagy ramps up. Cells step up their natural clean-up and recycling of damaged components.
These timings are approximate and vary from person to person based on your last meal, activity and metabolism.
How to Use This Fasting Tracker
- Pick a protocol — 16:8, 18:6, 20:4, OMAD or a custom number of hours.
- Press Start right after your last meal to open your fasting window.
- Watch the HH:MM:SS counter climb and the progress bar fill toward your goal.
- Refresh or close the tab freely — your start time is saved, so the fast keeps running.
- When you hit your goal, the timer chimes and your eating window begins.
Intermittent Fasting Tips for Beginners
- Start with 14:10 or 16:8 and extend your fasting window only as it gets comfortable.
- Stay hydrated — water, black coffee and plain tea are fine during the fast.
- Break your fast with balanced, whole foods rather than a heavy sugar rush.
- Keep your eating window consistent day to day to build the habit.
- Listen to your body and stop if you feel unwell.
This page is general information, not medical advice. Talk to your doctor before starting intermittent fasting, especially if you are pregnant, diabetic, or taking medication.