The required amount of zakaat ul-Fitr is one saa‘ of wheat, barley, rasins, dry yogurt, rice, corn, or similar items considered as basic foods. Abu Hanifah considered it permissible to set aside, as zakaat ul-Fitr, an equivalent value and also said that if the payer pays in wheat, one-half of a saa‘ would be sufficient. Abu Sa‘eed al-Khudree reported;
“We used to give on behalf of every child, elderly person, free person or slave during the lifetime of Allaah’s Messenger (صلى الله عليه و سلم), one saa‘ of food, or one saa‘ of dried yogurt, or one saa‘ of barley, or one saa‘ of dates, or one saa‘ of raisins as zakaat ul-Fitr. We continued to do so until Mu‘awiyyah came to us to perform Hajj, or ‘Umrah. He then addressed the people from the minbar and said; ‘I see that two mudds  of Syrian wheat equals one saa‘ of dates.’ The people accepted that.”
However, Abu Sa‘eed contended:
“I will continue to give as I used to give, one saa‘, as long as I live.” This is related by the group.
At-Tirmithee remarked: “This is acted upon by some scholars, in each case, they give one saa‘. This is the opinion of Ash-Shaafi‘ee, Ahmad, and Ishaaq. Some other people of knowledge, among the companions of the Prophet (صلى الله عليه و سلم) and otherwise, say one saa‘ from any type of grain except wheat, of which only half a saa‘ would be sufficient. This is the saying of Sufyaan ath-Thawree, Ibn al-Mubaarak, and the scholars of Kufah.”
From Sayyid Saabiq’s Fiqh us-Sunnah
With commentary by Muhammad Naasir ad-Deen al-Albaanee from Tamaam ul-Minnah fit-Ta‘leeq ‘alaa Fiqh as-Sunnah