My earlier answer had broken links to the websites, I've reposted the answer with the updated links.
The current limits for non-taxable profits are $250,000 for single, $500,000 for married. Your cost basis in the home establishes the amount to subtract from your net proceeds to determine your profit. Your cost basis includes the original purchase price, all purchase costs you paid, nearly all improvements that fall under the classification as a capital improvement (that is, not normal expenses and minor wear and tear). Your net proceeds includes the sales price, less all sales transaction related expenses, like commission, paying the owner's title policy, marketing expenses you incurred, etc.
If you owned the home more than 1 year, then the tax, if any, should be a capital gains tax, rather than the tax on ordinary income. As of today, the capital gains tax is only 15% or 5%, depending on your circumstances.
Reading the IRS website is like reading Greek, here are a couple of good overviews on the subject, in plainer English: