St. Louis is 10% more expensive than Springfield.
When comparing St. Louis, MO and Springfield, MO, the overall cost of living indices are 66 and 60 respectively (national median = 100). Rent is $58/month cheaper in Springfield, saving renters about $696/year.
Median household income is $9,295/year higher in St. Louis. Home values also differ significantly — the median in St. Louis is $185,100 compared to $165,200 in Springfield.
Both cities share the same state tax structure since they are in Missouri.
St. Louis vs Springfield — common questions
Other cost of living comparisons for St. Louis and Springfield