Fasting Calculator
Calculate the end time of your fast based on start time and duration. Useful for intermittent fasting schedules like 16:8, 18:6, or 24-hour fasts.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to use the Fasting Calculator
- Set your start time – Enter the time you began your fast using the Fasting Start Time field (default is 8:00 PM).
- Choose your fasting duration – Enter the number of hours in the Fasting Duration field (e.g., 16 for 16:8, 18 for 18:6, or up to 72 hours). Use half-hour increments if needed.
- Calculate – Click the Calculate End Time button or press the Enter key.
- Read your result – The end time appears in 12-hour format with AM/PM. A brief explanation of the calculation is shown below.
Note: All times are in 24-hour input format (e.g., 20:00 for 8 PM). The result automatically converts to 12-hour format. Duration must be between 1 and 72 hours.
Previous Results
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Frequently Asked Questions
A fasting calculator helps you determine the end time of your fast based on when you started and how long you plan to fast.
The end time is calculated by adding the fasting duration to the start time. For example, if you start at 8 PM and fast for 16 hours, your fast ends at 12 PM the next day.
Yes, you can enter any duration from 1 to 72 hours, making it suitable for various intermittent fasting schedules like 16:8, 18:6, or longer fasts.
