What is the minimum taxable amount (nisab) for grain zakat by weight?

The zakatable threshold (nisab) for grains is five wasqs, according to the Prophet's (peace be upon him) saying: "There is no sadaqah (zakat) on less than five wasqs of dates or grain." A wasq is sixty sa's, and a sa' is four mudds, and a mudd is approximately 560 grams. So, the nisab in kilograms is approximately 672 kilograms of good quality wheat.