Found this site that has a subsidy calculator: National Health Care Calculator
The interesting thing to me was in the notes section that describes the bases for the amount of subsidy: National Health Reform Calculator
For individuals with household income below 400 percent FPL who purchase coverage in the Marketplace, the law limits individuals' premium contributions to a set percentage of household income. The calculator returns the maximum contribution towards the premium and the estimated unsubsidized age-adjusted silver plan premium. If the monthly premium is less than the maximum premium contribution, the household will pay the premium without subsidy. The premium caps range from 3.0 percent of income at 133 percent FPL to 9.5 percent of income at 300 through 400 percent FPL. The premium percentage cap will be 2.0 percent for households with income below 133 percent FPL, applicable to legal immigrants who are not eligible for Medicaid. This cap is not shown in the calculator as most individuals with income below 133 percent FPL will be eligible for Medicaid. The calculator uses 2013 FPLs, which will be used by the Marketplace during the open enrollment period for the 2014 plan year.
I thought this was of interest since I had not seen this level of detail before and thought I would share.