Lot Size Calculator: Feet by Feet to Acres
Enter the frontage and depth from a listing or plat and see the lot in acres, square feet and square metres, set against a quarter, half and whole acre. Add your zoning setbacks to see how much of it you can build on.
Acres
0.3444
Square feet
15,000
Square metres
1,393.5
Side of an equal square
122.5 ft
Your lot against familiar sizes
Percentages show your lot as a share of each reference size.
How much of the lot can I build on? (enter your zoning rules)
Setbacks and lot coverage limits are set by your local zoning code and vary by district, so this calculator does not assume any. Look up the figures for your zone (the planning or zoning office will have them) and enter them here. Setbacks apply to rectangular lots only.
Area in square feet divided by 43,560 gives acres. The median new-home lot is for new single-family detached homes sold in 2025, from the Census Bureau Survey of Construction as reported by NAHB: 8,543 sq ft, or 0.196 acres.
Common lot dimensions in acres
Exact area for widths and depths you see on listings and plats.
| Dimensions (ft) | Sq ft | Acres |
|---|---|---|
| 25 x 100 | 2,500 | 0.0574 |
| 40 x 100 | 4,000 | 0.0918 |
| 50 x 100 | 5,000 | 0.1148 |
| 50 x 150 | 7,500 | 0.1722 |
| 60 x 120 | 7,200 | 0.1653 |
| 75 x 100 | 7,500 | 0.1722 |
| 75 x 150 | 11,250 | 0.2583 |
| 80 x 125 | 10,000 | 0.2296 |
| 100 x 100 | 10,000 | 0.2296 |
| 100 x 150 | 15,000 | 0.3444 |
| 100 x 200 | 20,000 | 0.4591 |
| 150 x 150 | 22,500 | 0.5165 |
| 66 x 330 | 21,780 | 0.5000 |
| 132 x 165 | 21,780 | 0.5000 |
| 66 x 660 | 43,560 | 1.0000 |
| 208.71 x 208.71 | 43,560 | 1.0000 |
| 330 x 660 | 217,800 | 5.0000 |
| 660 x 660 | 435,600 | 10.0000 |
| 1320 x 1320 | 1,742,400 | 40.0000 |
How deep a lot needs to be for a given acreage
Depth in feet needed to reach each acreage at common frontages, and the side of an equivalent square.
| Acreage | Square | 50 ft wide | 75 ft wide | 100 ft wide | 150 ft wide |
|---|---|---|---|---|---|
| 0.1 acres4,356 sq ft | 66.0 | 87.1 | 58.1 | 43.6 | 29.0 |
| 0.25 acres10,890 sq ft | 104.4 | 217.8 | 145.2 | 108.9 | 72.6 |
| 1/3 acre14,520 sq ft | 120.5 | 290.4 | 193.6 | 145.2 | 96.8 |
| 0.5 acres21,780 sq ft | 147.6 | 435.6 | 290.4 | 217.8 | 145.2 |
| 1 acre43,560 sq ft | 208.7 | 871.2 | 580.8 | 435.6 | 290.4 |
| 2 acres87,120 sq ft | 295.2 | 1,742.4 | 1,161.6 | 871.2 | 580.8 |
| 5 acres217,800 sq ft | 466.7 | 4,356.0 | 2,904.0 | 2,178.0 | 1,452.0 |
"Square" is the length of each side if the lot were square. All figures in feet.
Lot size questions
How do I work out how many acres a lot is from its dimensions?
Multiply the frontage by the depth to get square feet, then divide by 43,560. A 100 by 150 foot lot is 15,000 square feet, which is 0.3444 acres. If the front and rear widths differ, average them before multiplying by the depth. For a triangle, multiply the base by the height and halve it.
What are the dimensions of half an acre?
Half an acre is 21,780 square feet, and any rectangle with that area qualifies. As a square it is about 147.6 feet on each side. Other exact combinations include 66 by 330 feet (one chain by half a furlong), 132 by 165 feet, and 100 by 217.8 feet. The table on this page gives the depth needed at common frontages.
How many feet is an acre on each side?
An acre has no fixed shape. If it is a square, each side is the square root of 43,560, about 208.71 feet. The historical acre was a strip one chain (66 feet) wide and one furlong (660 feet) long, which is also exactly 43,560 square feet.
How many acres is 100 by 100 feet?
A 100 by 100 foot lot is 10,000 square feet, which is 0.2296 acres, a little under a quarter acre (10,890 square feet). A quarter acre with 100 feet of frontage needs a depth of 108.9 feet.
How big a house can I build on my lot?
That depends on your local zoning code, not on the acreage alone. Setbacks keep buildings a set distance from each boundary, and many codes also cap lot coverage, the share of the lot that buildings may cover. Enter your zone's setbacks and coverage limit in the calculator to see the largest ground footprint they allow; height limits then decide how many storeys you can add on top.