In the first place, we’d like to make it clear that spending for the sake of Allah is one of the best deeds. The merit is greater when this spending happens during the blessed month of Ramadan. the main purpose of zakat al-fitr is to provide those who fasted with the means of making up for their errors during the month of fasting. Zakat al-fitr also provides the poor with the means to celebrate the festival of breaking the fast along with the rest of the Muslims.
Sheikh Yusuf Al-Qaradwi, states the following: “The amount of zakat al-fitr does not vary as it is estimated by Islamic Law as one saa` (2.176 kilograms or 4.797 pounds) and it was fixed by the Prophet (peace and blessings be upon him). The wisdom behind estimating zakat al-fitr by the saa`, in my understanding, is due to two reasons:
First, money was a rare means of dealing among the Arabs, especially the Bedouins. If you came to one of them and said to him you should pay such-and-such sum of dirhams or dinars, he would not have such amount of money. He would have only foodstuffs such as dates, raisins, barley, etc. This was what made the Prophet (peace and blessings be upon him) fix zakat al-fitr at one saa`.
Second, the purchasing power of money varies from time to another. Sometimes the value of the riyal decreases and therefore its purchasing power decreases, too, and sometimes the purchasing power rises in the markets. So, estimating the amount of zakat al-fitr by a fixed amount of money would make it fluctuate and be unstable. That is why the Prophet (peace and blessings be upon him) fixed zakat al-fitr by an amount that does not vary or fluctuate. This amount is the saa`, which is usually considered as a sufficient food for one family for a day. The Prophet (peace and blessings be upon him) identified the common foodstuffs in his age, which included but was not limited to dates and barley.
Based on the above, scholars maintained that paying zakat al-fitr from the staple food in a certain area is permissible, whether this food is wheat, rice, corn, etc.
The saa` is a measure that equals approximately 2 kilograms or 5 pounds. According to Abu Hanifah, it is allowed to pay zakat al-fitr in cash. If the one who gives zakat al-fitr is rich, it would be better for him to pay more than the amount of one saa`, as the food is not limited to rice, but there should be meat, sauce, vegetables, fruit, etc. along with the rice.”