Calculate your lot size two ways: multiply your dimensions, or trace your property on satellite imagery and let the area total up automatically.
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From dimensions. If your lot is rectangular and you know its width and depth, from a survey, plat map, or listing, the math is one multiplication: width × depth. Most suburban lots are close enough to rectangular for this to work well.
From boundary tracing. If your lot is any other shape, pie-shaped on a cul-de-sac, a corner lot, an L with a flag driveway, enter your address at LotSite, see the property on satellite imagery, and trace the boundary. The area is calculated automatically from the cells you paint, no geometry required. This also works when you simply don't know your dimensions.
Area (sq ft) = Width (ft) × Depth (ft)
To get acres, divide square feet by 43,560. One caution: the formula only works for rectangles. Irregular lots need to be broken into simpler shapes and summed, or traced on satellite imagery, which is usually faster and less error-prone.
Worked example: the pie-shaped lot. Cul-de-sac lots taper, so treat them as trapezoids. Average the front and back widths, then multiply by depth. Say yours has 40 ft of street frontage, spreads to 110 ft across the back, and runs 130 ft deep: (40 + 110) ÷ 2 × 130 = 9,750 sq ft. Use the frontage alone and you'd get 5,200 sq ft. Barely half the real answer, which is exactly the mistake that leaves tapered-lot owners under-ordering materials.
Triangles handle everything else. Any straight-sided lot can be split into triangles, and each triangle is ½ × base × height. An L-shaped lot is two rectangles; a five-sided corner lot is a rectangle plus a triangle. Sketch the shape, sum the pieces, and sanity-check the total against a trace. If the two disagree by more than a few percent, one of your assumed dimensions is wrong.
Don't trust perimeter intuition. Two lots with the same boundary length can enclose very different areas: a 100 × 100 ft lot and a 40 × 160 ft lot both have 400 ft of perimeter, but the first is 10,000 sq ft and the second only 6,400. Fence cost tracks the perimeter; nearly everything else tracks the area, which is why it pays to know both numbers for your own lot.
1. Property survey: the most accurate source; every boundary segment is measured by a licensed surveyor. 2. Plat map: the recorded subdivision map at your county recorder's office, definitive for most residential lots. 3. County assessor records: many counties publish lot dimensions along with the parcel record.
4. Real estate listings: often show dimensions in "60 x 120" form, though figures can be approximate. 5. Measure them yourself: physically with a tape or wheel, or trace and measure distances on satellite imagery via the property dimensions lookup page. For the full dimension-by-address guide, see lot dimensions by address.
Common conversions at a glance. Divide sq ft by 43,560 for anything in between.
| Square Feet | Acres |
|---|---|
| 5,000 sq ft | 0.115 |
| 7,500 sq ft | 0.172 |
| 10,890 sq ft | 0.25 |
| 21,780 sq ft | 0.50 |
| 43,560 sq ft | 1.00 |
| 87,120 sq ft | 2.00 |
| 217,800 sq ft | 5.00 |
Landscaping quotes are priced by area, and fence estimates by perimeter. Both start from your lot's numbers. Fertilizer and seed are dosed per 1,000 sq ft of lawn. In real estate, lot size drives comparable value, and if your property tax assessment lists a bigger lot than you actually have, a measurement is the first step of an appeal. Look up any address on the property size lookup page, or see lot size by address for how the sources compare.
Irregular lot? Trace it on satellite imagery. The math is automatic.
Free. No signup. Works nationwide. Open the measurement tool for irregular lots, or lot size by address for lookup methods.