I am an Indian student on F1 visa and am located in California. I want to know how much tax will be deducted from my salary, i.e, $4000/month. And from that charged tax how much can I get back as an international student?

What city... some cities have a wage tax, and your county tax will vary based on where you live in the state, unless you are only interested in rough numbers.

I am located in Santa Clara county.

At $48K per year, and assuming you are single, you are in the 25% marginal tax bracket. That means the LAST dollar you earn in 2010 will be taxed at 25%. It starts at zero, then 10%, then 15% on a progressive (the more you make, he higher the tax) scale.

Expect to pay about $6,000 to the IRS and $2,000 to California. Any excess withheld wll be refunded to you.

Note that you are EXEMPT from FICA (social Security and Medicare) taxes. See IRS Pub 519, page 54-55. You can download that pub from Internal Revenue Service (http://www.irs.gov), print those pages off and show itto your employer if they are withholding these taxes.