2020 census As of the
2020 census, Gardner had a population of 1,366. The median age was 41.6 years. 20.6% of residents were under the age of 18 and 16.7% of residents were 65 years of age or older. For every 100 females there were 104.2 males, and for every 100 females age 18 and over there were 104.7 males age 18 and over. 0.0% of residents lived in urban areas, while 100.0% lived in rural areas. There were 577 households in Gardner, of which 26.7% had children under the age of 18 living in them. Of all households, 46.8% were married-couple households, 22.9% were households with a male householder and no spouse or partner present, and 22.2% were households with a female householder and no spouse or partner present. About 31.7% of all households were made up of individuals and 12.3% had someone living alone who was 65 years of age or older. There were 619 housing units, of which 6.8% were vacant, at an average density of . The homeowner vacancy rate was 3.3% and the rental vacancy rate was 6.5%. The population density was .
Income and poverty The median income for a household in the village was $67,441, and the median income for a family was $71,544. Males had a median income of $56,250 versus $40,383 for females. The
per capita income for the village was $35,716. About 5.1% of families and 6.2% of the population were below the
poverty line, including 9.3% of those under age 18 and 8.4% of those age 65 or over. ==Education==