What the numbers mean
A $75,000 salary in San Francisco gives you the equivalent of $35,954 in purchasing power after accounting for state income taxes (7.0%) and the local cost of living. The same salary in Denver gives you $56,457 — a difference of +57%.
Median rent in Denver runs about $1,800/month — roughly $1,600/month less than San Francisco's $3,400. That's $19,200/year back in your pocket before you factor in anything else.
These numbers use a cost-of-living index where 100 = national average. San Francisco's index of 194 means it costs 194% of the national average to maintain the same lifestyle. Denver's is 127.