Square Mile to Square Foot

The Public Land Survey System (PLSS), established by the Land Ordinance of 1785, divided US territory into 6-mile × 6-mile townships (36 mi²) and 1-mile × 1-mile sections (1 mi², = 640 acres). This grid underlies property deeds, county boundaries, and road layouts across most of the western US. Switching to km² would require legal redefinition of millions of property descriptions — a transition with no political appetite.

Manhattan borough is 22.83 mi² (59.1 km²), making it one of the most densely populated places on Earth at about 71,000 people/mi². The island itself (excluding water area) is about 13.4 mi². For comparison, the entire city of New York is 302.6 mi², of which 36% is water. Central Park occupies about 1.3 mi² — nearly 6% of Manhattan's land area.

Alaska is by far the largest at 663,268 mi² — over twice the size of Texas (268,596 mi²). Alaska is so large it would be the 18th largest country in the world if independent. For perspective, the entire Lower 48 states fit within Alaska about 5 times over in land area. Alaska also has the longest coastline of any US state at 33,904 miles.

One square mile is a square about 1,609 m (just over a mile) on each side. A standard city grid: in Chicago, the city blocks are laid out on a 1-mile square grid, so 16 standard blocks (4 × 4) = 1 mi². Walking the perimeter of 1 mi² takes about 1 hour at a moderate pace. In rural areas, US county road grids typically run every mile, creating a visible 1 mi² checkerboard visible from aircraft.

The PLSS divides most land west of the Appalachians into a grid of 6×6 mile townships, each split into 36 sections of 1 mi² (640 acres). Established by the Land Ordinance of 1785, it still defines property boundaries for roughly 1.5 billion acres across 30 states. County roads in the Midwest often follow PLSS section lines, creating the visible checkerboard pattern from the air. The system predates metric adoption and is so embedded in US land titles that converting to km² would require re-recording tens of millions of deeds.

There is no single national standard in the US. ANSI Z765 (the American National Standard for Single-Family Residential Buildings) defines finished, above-grade living area heated and cooled — excluding garages, unfinished basements, and attics. However, real estate agents and appraisers often include finished basements in listings, leading to inflated figures. The UK uses the RICS Measuring Practice guide, also excluding garages but with specific rules for sloped ceilings below 1.5 m.

The UK officially adopted metric in 1965 but real estate listings use both ft² and m². Estate agents find ft² still resonates with buyers who grew up with it — a 1,000 ft² flat sounds substantial, while 93 m² sounds modest (they're the same). New-build developers often use m² in technical specifications but ft² in marketing materials. Scotland has moved more decisively toward m² in official planning documents.

In the US, flooring costs per ft²: basic laminate $1–3/ft², hardwood $3–10/ft², porcelain tile $2–8/ft², luxury vinyl plank $2–5/ft², carpet $1–5/ft². Installed costs are roughly double the material cost. A 1,000 ft² apartment floor costs $3,000–15,000 to floor depending on material choice — a calculation every US homeowner makes in ft², not m².

A rough rule of thumb is 1 BTU per hour per ft² (or about 12,000 BTU/h = 1 ton of cooling per 1,200 ft²). A 1,500 ft² home typically needs 1.5–2 tons of cooling. Actual sizing (Manual J calculation) factors in insulation, window area, climate zone, and ceiling height — but ft² remains the quick-estimate starting point for US HVAC contractors.

New York City apartments historically had no minimum size until 2021, when the city mandated a minimum of 400 ft² for new units. San Francisco minimum is 220 ft². Tokyo allows units as small as 95 ft² (about 9 m²) under certain zoning. The world's smallest commercially sold apartment is probably in Hong Kong at about 75 ft² — including the bathroom, kitchen, and sleeping loft.