Area Calculator
Convert land area units instantly, or calculate a plot, circle, triangle, or trapezoid from its dimensions.
Land Area Converter
- Acres
- Square feet
- Square meters
- Hectares
- Square yards
Results use exact conversion factors and display up to 2 decimal places. Positive values below 0.01 display as < 0.01.
Irregular Plot Area
For an irregular plot, enter the four sides and one diagonal.
Unmarked lengths use the selected unit. Explicit units, including 12'6", override it.
Follow A → B → C → D around a non-crossing boundary. Diagonal AC must lie inside the plot, splitting it into ABC and ACD.
Plot Area
- Square meters
- Square feet
- Acres
Both triangles use Heron's formula: √(s(s − a)(s − b)(s − c)), where s = (a + b + c) ÷ 2. Displayed areas are rounded to 2 decimal places.
Shape Area Calculator
Measure from the center to the edge. Area = π × radius².
Height is perpendicular to the base. Area = base × height ÷ 2.
The bases must be parallel; height is the perpendicular distance between them. Area = (top base + bottom base) × height ÷ 2.
Unmarked lengths use the selected unit. Explicit units, including 12'6", override it.
Circle Area
- Square meters
- Square feet
- Acres
Results are rounded to 2 decimal places.
Acres to Square Feet
An acre measures area, not a particular shape. One acre equals exactly 43,560 square feet, whether the boundary is long and narrow, nearly square, or irregular. Multiply an acreage by 43,560 to express the same land area in square feet. To go in the other direction, divide the square foot value by 43,560.
For example, a quarter acre contains 10,890 square feet, while half an acre contains 21,780. Two acres contain 87,120 square feet. These conversions change the unit only; they do not tell you the lengths of the boundary lines.
Use the table for common parcel sizes, or enter your own value in the converter above. Its calculations use exact conversion factors before rounding the displayed results. Keep the original measurements when comparing parcels, especially when small differences matter.
| Acres | Square feet |
|---|---|
| 0.25 | 10,890 |
| 0.5 | 21,780 |
| 1 | 43,560 |
| 2 | 87,120 |
| 5 | 217,800 |
| 10 | 435,600 |
| 40 | 1,742,400 |
How to Measure Land Area
Start by identifying the boundary of the area you want to measure. For a rectangular plot, measure the length and the perpendicular width, then multiply those measurements. A plot measuring 30 meters by 20 meters has an area of 600 square meters. This shortcut assumes the corners are right angles; four unequal or angled sides need a different approach.
For a simple irregular quadrilateral, label the corners A, B, C, and D in order around the boundary. Measure sides AB, BC, CD, and DA, plus diagonal AC. Choose a diagonal that lies inside the plot. It divides the outline into triangles ABC and ACD. The calculator applies Heron's formula to each triangle and adds their areas.
Use one consistent length unit for all five measurements. Each group of three sides must form a valid triangle. Curved boundaries, crossing edges, or extra corners need a different breakdown. An outside diagonal cannot be used with this addition method.
Acres vs Hectares vs Square Feet
Acres and hectares both describe land area, but their sizes differ. An acre is exactly 4,046.8564224 square meters. A hectare is exactly 10,000 square meters, making it about 2.47105 acres. The hectare belongs to the metric system and is often used for agricultural land and larger parcels.
Square feet provide a smaller unit commonly used in United States property descriptions. There are exactly 43,560 square feet in an acre. Changing between these units does not change a parcel's shape or boundaries. Choose the unit that matches your source measurements or comparison, and use the converter to keep the figures consistent across listings, maps, or project notes.
| Unit | Commonly used for | Conversion |
|---|---|---|
| Acre | US land parcels and agricultural property | 1 acre = 43,560 sq ft = 4,046.8564224 m² |
| Hectare | Metric land and agricultural measurements | 1 ha = 10,000 m² ≈ 2.47105 acres |
| Square foot | US property area measurements | 1 sq ft = 0.09290304 m² |
Area Calculator FAQ
How many square feet are in an acre?
One acre contains exactly 43,560 square feet. This relationship applies to any shape of land with an area of one acre. The boundary lengths can vary, so acreage alone does not determine the distance along each side.
How do I calculate the area of a plot of land?
For a rectangular plot, multiply its length by its perpendicular width. For a simple four-sided plot, measure the four boundary sides and an interior diagonal. Enter those five lengths in the plot calculator, using a consistent unit.
How do I convert acres to square feet?
Multiply the number of acres by 43,560. For example, 0.5 acre equals 21,780 square feet, and 2 acres equal 87,120 square feet. The converter accepts an acreage and displays its equivalent in all five supported area units.
What is the difference between an acre and a hectare?
A hectare is larger than an acre. One hectare equals exactly 10,000 square meters, while one acre equals exactly 4,046.8564224 square meters. That makes one hectare approximately 2.47105 acres and one acre approximately 0.404686 hectare.
How do you calculate the area of an irregular shape?
Divide the outline into simpler shapes with known dimensions, calculate each area, and combine them without overlapping. This page handles a simple quadrilateral using four sides and an interior diagonal. Curves, crossing boundaries, or more corners require a different breakdown.
How do I find the area of a circle?
Choose Circle and enter the radius, measured from the center to the edge. The area is pi times the radius squared. If you know the diameter instead, divide it by two before entering the radius in the calculator.
How many acres is 10,000 square feet?
Divide 10,000 by 43,560 to get approximately 0.229568 acre, or about 0.23 acre when rounded to two decimal places. This is slightly less than a quarter acre, which contains exactly 10,890 square feet.
What is the formula for the area of a triangle?
The area of a triangle is its base multiplied by its perpendicular height, divided by two. For example, a base of 10 meters and a height of 6 meters give 30 square meters. Use the perpendicular height, not a sloping side.