Seattle is 42% more expensive than Thornton.
When comparing Seattle, WA and Thornton, CO, the overall cost of living indices are 196 and 138 respectively (national median = 100). Rent is $188/month cheaper in Thornton, saving renters about $2,256/year.
Median household income is $20,999/year higher in Seattle. Home values also differ significantly — the median in Seattle is $912,100 compared to $482,200 in Thornton.
Washington has no state income tax, giving Seattle residents a significant tax advantage over Colorado's 4.4% rate.
Seattle vs Thornton — common questions
Other cost of living comparisons for Seattle and Thornton