It is highly important that you consult a scholar while calculating your zakat as it is the purification of your wealth and it only comes once a year. So to ensure that you get it right first time it is highly advised that you use a zakat calculator, read the fiqh books to see the rulings for zakat, and also consult a scholar.
There are fiver pillars in Islam and one of them is Zakat.
Zakat is the fourth pillar of Islam. Zakat means setting apart for Allah every year a certain portion of one’s savings and wealth (generally 2.5 percent) and spending it upon religious duties and on needy members of the community. The fulfillment of this duty is, in fact, a kind of reminder that all one has is in trust for Allah. Man should, therefore, hold nothing back from Allah. To whatever one may amass in one’s lifetime, one’s own personal contribution is insignificant. If the Supreme Being, who is at work in the heavens and on the earth, refused to co-operate with man, there would be nothing that the latter could accomplish single-handed. He would not be able to plant so much as a single seed to make things grow. Nor could he set up any industries, or carry out any other such enterprise. If Allah were to withdraw any one of His material blessings, all our plans would go awry, and all our efforts would be brought to naught.
Zakat is the practical recognition of this fact through the expenditure of money. Islam requires man to consider his personal wealth as belonging to Allah and, therefore, to set apart a portion for Him. No maximum limit has been prescribed, but a minimum limit has definitely been fixed. According to statutory Zakat, each individual must abide by this and spend a fixed minimum percentage of his wealth every year in the way prescribed by Allah. In so spending his wealth, he is permitted neither to belittle the recipient nor to make him feel obliged or grateful to himself. His wealth must be given to the needy in the spirit of its being a trust from Allah which he is making over to the genuine title-holders. He should feed others so that he himself is fed in the Hereafter, and he should give to others so that he himself is not denied succor by Allah in the next world.
Zakat is a symbol of ones obligation to recognize the rights of others and to be in sympathy with them in pain or in sorrow. These sentiments should become so deep-rooted that one begins to regard one’s own wealth as belonging, in part, to others. Moreover, one should render service to others without expecting either recognition or recompense. Each individual should protect the honor of others without hope of any gain in return. He should be the well-wisher of not just friends and relations, but of all members of society. Zakat, first and foremost, makes it plain to people that their entire possessions are gifts of Allah, and, secondly, dissuades the servants of Allah from living in society as unfeeling and selfish creatures. Indeed, throughout their entire lives, they must set aside some portion for others.