Metro Dayton or the Miami Valley, or more formally the Dayton–Kettering–Beavercreek, OH Metropolitan Statistical Area, as defined by the United States Census Bureau, is an area consisting of three counties in the Miami Valley region of Ohio and is anchored by the city of Dayton. As of 2020, it is the fourth-largest metropolitan area in Ohio and the 73rd-largest metropolitan area by population in the United States with a population of 814,049.

The Dayton–Springfield–Kettering Combined Statistical Area is a Combined Statistical Area in the U.S. state of Ohio, as defined by the United States Census Bureau. It consists of the Dayton Metropolitan Statistical Area (the counties of Montgomery, Greene and Miami); the Springfield, Ohio metropolitan area (Clark County); the Urbana Micropolitan Statistical Area (Champaign County); the Greenville Micropolitan Statistical Area (Darke County); and the Sidney Micropolitan Statistical Area (Shelby County). As of the 2020 Census, the CSA had a population of 1,086,512.

According to an article in The Cincinnati Enquirer, as Greater Cincinnati grows northward through Butler County, its outer suburbs are expected to expand and begin to overlap the Greater Dayton area. Such a concept has already received the nickname of "Daytonnati." The two metropolitan areas were expected to be combined after tabulation of the 2010 Census, but this did not occur. As of the 2020 census this has still not occurred due to criteria not being met for combined area designation

Greater Dayton is part of the Great Lakes Megalopolis containing an estimated 54 million people.

As of the census 2010, there were 799,232 people, 343,971 households, and 220,249 families residing within the MSA. The racial makeup of the MSA was 80.40% White, 14.90% African American, 0.20% Native American, 1.80% Asian, 0.01% Pacific Islander, 0.80% from other races, and 2.00% from two or more races. Hispanic or Latino of any race were 1.90% of the population.

The median income for a household in the MSA was $47,381, and the median income for a family was $59,770. Males had a median income of $38,430 versus $26,205 for females. The per capita income for the MSA was $25,436.

From the 2000 Census to the 2010 Census, the Dayton region has seen a shift in population from its urban core to more out-lying affluent suburbs. This is evidenced by a 10% growth in population in Englewood, a 19% population growth in Beavercreek, and a 40% population growth in Springboro. Smaller growths in the 2010 census in the Dayton area included Miamisburg, Centerville, Vandalia, and Fairborn. Many of Dayton's suburbs that saw declines in populations fared well from 2000 to 2010. Dayton's largest suburb, Kettering for example, only saw a 2.3% decline during the ten-year period and Huber Heights, Dayton's third largest suburb, saw a 0.3% decline in population.

The Dayton Metropolitan Statistical Area formerly included Clark County and Preble County. In 2005, Clark County containing Springfield, Ohio separated from the Dayton MSA to create their own MSA named Springfield Metropolitan Statistical Area. As a result of new Census criteria to delineate metropolitan areas, Preble County was eliminated from the MSA in 2013 as it no longer qualified for inclusion. A significant drop in population for the Dayton MSA is noted in the 2010 census because of these changes.