Washington is 61% more expensive than St. Petersburg.
When comparing Washington, DC and St. Petersburg, FL, the overall cost of living indices are 171 and 106 respectively (national median = 100). Rent is $358/month cheaper in St. Petersburg, saving renters about $4,296/year.
Median household income is $33,169/year higher in Washington. Home values also differ significantly — the median in Washington is $724,600 compared to $331,500 in St. Petersburg.
Florida has no state income tax, giving St. Petersburg residents a significant tax advantage over District of Columbia's 10.75% rate.
Washington vs St. Petersburg — common questions
Other cost of living comparisons for Washington and St. Petersburg