The Social Security /Medicare combined tax rate is 7.65%.
This tax rate is the combined rate for Social Security and Medicare. The Social Security portion (OASDI) is 6.20% on earnings up to the applicable taxable maximum amount (see attached screenshot)).
At the 2016 maximum earnings for SS ($118,500) , the annual tax would be $7,347.
See: https://www.ssa.gov/news/press/factsheets/colafacts2016.html