[pkaye]

Social Security contributions in the US are 6.2% for the employee and 6.2% for the employer. There is a yearly max contribution income threshold which slowly is adjusted every year.

I think you need about 10 years on contribution to get the maximum benefits possible though you can get some of it earlier for permament disabilities. At retirement age the the average of you top 35 years income is used to calculate how much benefits your earned. Those in the lower income bracket get a higher percent and the curve flattens out at higher income.