According to the United States Census Bureau, the city has a total area of 80.3 km² (31.0 mi²). 76.4 km² (29.5 mi²) of it is land and 3.9 km² (1.5 mi²) of it (4.84%) is water.
The city's official motto is "Beauty and Progress."
Miramar is Spanish for "Sea view" or "sea sight", though it is not located directly near the Atlantic Ocean. The city is bordered by the following municipalities:
There were 23,058 households out of which 48.2% had children under the age of 18 living with them, 56.0% were married couples living together, 19.1% had a female householder with no husband present, and 19.1% were non-families. 14.3% of all households were made up of individuals and 3.3% had someone living alone who was 65 years of age or older. The average household size was 3.15 and the average family size was 3.48.
In the city the population was spread out with 31.0% under the age of 18, 8.6% from 18 to 24, 35.4% from 25 to 44, 18.7% from 45 to 64, and 6.3% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 90.8 males. For every 100 females age 18 and over, there were 85.0 males.
The median income for a household in the city was $50,289, and the median income for a family was $52,952. Males had a median income of $34,145 versus $28,283 for females. The per capita income for the city was $18,462. About 7.0% of families and 8.2% of the population were below the poverty line, including 9.8% of those under age 18 and 8.5% of those age 65 or over.
