Intention to Fast Before Half the Day is Over

1. If one did not eat or drink anything, (or have intimacy with the husband,) then forming the intention to fast on the day of Ramadhan an hour before Zawaal is valid.
2. The actual rule is that if the intention was made before half the day passed by then the fast is valid.
3. The method of determining half of the day is to see the total number of hours from Subh Saadiq to Sunset and divide the total by half. Then add the quotient to the time of Subh Saadiq. This will be what is termed as Nisfun Nahaar (midday in the Shariah).
4. Example: Subh Saadiq is 4:30am and Sunset is 6:30pm. Thus, the total number of hours of fasting is 14. Half of 14 is 7. Add 7 to the Subh Saadiq time which is 4:30am = 11:30am. Therefore, the intention should be made before 11:30am.

(Behshti Zewar)