18:6 — janela alimentar (h)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The 18:6 eating window calculator helps determine precise fasting and feeding periods for the 18:6 intermittent fasting method. This model uses 18 hours of fasting followed by a 6-hour eating window, starting from a user-defined time.
It operates on a simple formula: the eating window is fixed at 6 hours, while fasting occupies the remaining 18 hours of a 24-hour cycle. The tool automatically adjusts start and end times based on the initial input.
Use this calculator to plan meals and snacks within the 6-hour window, ensuring strict fasting adherence. Many users align the window with their daily routine, avoiding fasting during nighttime hours.
Before starting intermittent fasting, consult a doctor or nutritionist. This method may not be suitable for individuals with specific medical conditions, pregnant women, or those with a history of eating disorders.
Frequently asked questions
What is the 18:6 intermittent fasting method?
It's a fasting model involving 18 hours of fasting followed by 6 hours of daily eating, in a continuous cycle.
How do I use the calculator?
Enter your desired eating window start time; the tool will automatically calculate fasting and eating periods.
Can I adjust the eating window?
No, the calculator fixes the window at 6 hours. For custom models, use the personalized fasting calculator.
Is it safe for beginners?
It can be adapted, but consulting a professional is recommended, especially for those with a history of overeating or low blood pressure.
How to handle hunger during fasting?
Drink water, unsweetened tea, or coffee. Avoid foods that break your fast before the scheduled window.