There is no set amount or percentage dictated by the Quran. Usually the customary amount is ~2.5% of capital assets earned in a year. And apparently somewhere

There is no set amount or percentage dictated by the Quran. Usually the customary amount is ~2.5% of capital assets earned in a year. And apparently somewhere around 20% on mining income, which obviously is only applicable to small number of people who own interests in mining operations.