ANSWER:
You must give your zakat on your savings if they are equivalent or beyond the value of 595 gms of silver.
THRESHOLD FOR ZAKAT:
The threshold (nisab) of money is the value of 595 grams of silver which is about 300$. You try and set a date and on that day, you calculate how much you have and give 2.5% in zakat. Every lunar year, you do this process on that date.