The Fasting Calculator helps you track your intermittent fasting progress in real time. Whether you follow 16:8, 18:6, 20:4, or a custom schedule, this tool shows your elapsed fasting time, remaining time, and when your eating window opens. All calculations run locally in your browser — your data stays private.
How to Use This Calculator
- 1Set your start time: Enter the date and time when you began your fast.
- 2Choose a method: Select 16:8, 18:6, 20:4, or set a custom duration.
- 3Track automatically: Progress updates in real-time — no button to click.
- 4Check anytime: The auto-refresh keeps your elapsed time accurate every 60 seconds.
Popular Fasting Methods
Why Track Your Fast?
Visual progress tracking helps you stay committed to your fasting goals.
Always know exactly when your eating window opens and closes.
Track how different fasting durations affect your energy and wellbeing.
Elapsed time updates every 60 seconds automatically — no manual refreshes.
Frequently Asked Questions
Intermittent fasting is an eating pattern that cycles between periods of fasting and eating. Common methods include 16:8 (16 hours fasting, 8 hours eating) and 18:6 (18 hours fasting, 6 hours eating).
Intermittent fasting may help with weight loss, improved insulin sensitivity, cellular repair (autophagy), and brain health. Always consult your doctor before starting any fasting regimen.
Yes, water, black coffee, and unsweetened tea are generally allowed during fasting periods. They do not break your fast and help keep you hydrated.
Yes, the calculator updates automatically every 60 seconds to show your current elapsed fasting time and progress. No need to click anything.
Yes, select "Custom Duration" and set your own fasting duration between 1 and 23 hours. The calculator adapts all results to your custom schedule.
Absolutely. All calculations happen locally in your browser. Your fasting data never leaves your device.
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