What is the nisab (minimum amount upon which Zakat is due) for Zakat, by which gold standard is it measured, how is Zakat calculated on saved salary that might be used to buy a house, and is Zakat obligatory if the money falls below the nisab then returns to it, or if it is spent before a full year passes?

The nisab for currencies is the equivalent of 85 grams of gold or 595 grams of silver, and the obligatory amount to be given is two and a half percent.

Zakat is obligatory on saved money if it reaches the nisab and a full lunar year (hawl) has passed on it. The hawl begins from the day the money reaches the nisab, either by itself or when combined with other funds.

Preparing money to buy a house does not prevent zakat from being obligatory on it. If the money falls below the nisab before the end of the hawl, then zakat is not obligatory on it.