The median lot size of a new single-family detached home sold in 2018 stands at 8,567 square feet, or just under one-fifth of an acre. This is just 7 square feet larger but statistically not different from the 2017 median. In 2015, the median lot size fell under 8,600 square feet for the first time since Census Bureau’s Survey of Construction (SOC) started tracking the series for single-family detached homes. It remained in this record low territory ever since.
The shrinking median lot size largely reflects the shift in speculatively built (or spec) home building towards smaller lots. A decade ago 28% of all sold single family detached homes were sitting on lots under 0.16 acres and 19% were occupying between 0.16 and 0.25 acres. In 2018, these shares increased to 32% and 27%, respectively. At the other end of the lot size distribution, the share of spec homes built on lots over half an acre shrunk from 14% in 2008 to 10% in 2018.
While nation’s production of spec homes shifts towards smaller lots, the regional differences in lot sizes persist. Looking at single-family detached spec homes started in 2018, the median lot size in New England is more than twice as large as the national median.
New England is known for strict local zoning regulations that often require very low densities. Therefore, it is not surprising that more than half of single-family detached spec homes started in New England are built on some of the largest lots in the nation, with more than half of the lots exceeding half an acre. The East South Central is next on the list with the median lot occupying just slightly less than a third of an acre (0.3 acres).
In the South, the West South Central division stands out for starting half of single-family detached spec homes on lots under 0.17 acres. This is significantly lower than the median lot sizes in the other two southern divisions – 0.3 acres in the East South Central division and 0.21 acres in the South Atlantic division.
The Pacific division where densities are high and developed land is scarce has the smallest lots, with half of the lots being under 0.14 acres. The neighboring Mountain division also reports typical lots smaller than a national median, 0.17 acres.
The analysis above is limited to single-family detached speculatively built homes. Custom homes built on owner’s land with either the owner or a builder acting as the general contractor do not involve the work of a professional land developer subdividing a property. Therefore, in case of custom homes, lots refer to owner’s land area rather than lots in conventional sense. Nevertheless, the SOC reports lot sizes for custom homes and shows that they tend to have larger lots. The median lot size for custom single-family detached homes started in 2018 is about one acre.
For this analysis, the median lot size is chosen over average since averages tend to be heavily influenced by extreme outliers. In addition, the Census Bureau often masks extreme lot sizes and values on the public use SOC dataset making it difficult to calculate averages precisely, but medians (as the midpoint of a frequency distribution) remain unaffected by these procedures.