Area of a rectangle
A = l × wMultiply the length by the width. If length and width are measured in meters, the result is in square meters.
Rectangle Area Calculator
Calculate the area, perimeter, and diagonal of any rectangle. Enter its length and width, choose your measurement units, and get accurate results with formulas, step-by-step calculations, and area conversions.
Area = Length × Width
Perimeter calculator
Diagonal calculator
Multiple units
Free and instant
Enter rectangle dimensions
Enter positive measurements. Length and width can use different units.
A = l × w
Area equals length multiplied by width. Both dimensions must be expressed in the same unit before multiplying.
Your rectangle results
Results update when you calculate or change a value.
Rectangle area
50.00
m²
Based on a length of 10 m and a width of 5 m.
Perimeter
30.00 m
Diagonal
11.18 m
Length in meters
10.00 m
Width in meters
5.00 m
Area in square meters
50.00 m²
Area in square feet
538.20 ft²
A = 10 × 5 = 50 m²
Multiply the converted length by the converted width to find the rectangle's area.
Calculation steps
- Length = 10 m.
- Width = 5 m.
- Area = 10 × 5 = 50 m².
Rectangle area formulas
A rectangle has four right angles, and opposite sides are equal. Its area measures the surface inside its boundaries. The perimeter measures the total distance around the rectangle, while the diagonal is the straight-line distance between opposite corners.
Perimeter of a rectangle
P = 2(l + w)Add the length and width, then multiply the sum by two. Perimeter is expressed in linear units.
Diagonal of a rectangle
d = √(l² + w²)Use the Pythagorean theorem to calculate the diagonal from the length and width.
Length from area
l = A ÷ wIf the area and width are known, divide the area by the width to calculate the length.
Width from area
w = A ÷ lIf the area and length are known, divide the area by the length to calculate the width.
Area of a square
A = s²A square is a special type of rectangle whose length and width are equal to the side length s.
Rectangle area examples
These examples show how to calculate the area of rectangles with different dimensions and units.
| Length | Width | Calculation | Area | Perimeter |
|---|---|---|---|---|
| 10 m | 5 m | 10 × 5 | 50 m² | 30 m |
| 8 cm | 3 cm | 8 × 3 | 24 cm² | 22 cm |
| 12 ft | 7 ft | 12 × 7 | 84 ft² | 38 ft |
| 2.5 m | 1.2 m | 2.5 × 1.2 | 3 m² | 7.4 m |
| 100 cm | 50 cm | 100 × 50 | 5,000 cm² | 300 cm |
Rectangle area unit conversions
Area units are squared length units. Converting between them requires squaring the linear conversion factor. For example, 1 meter equals 100 centimeters, but 1 square meter equals 10,000 square centimeters.
| Area unit | Equivalent in square meters | Common use |
|---|---|---|
| 1 mm² | 0.000001 m² | Small components and precision measurements |
| 1 cm² | 0.0001 m² | Small surfaces and craft projects |
| 1 m² | 1 m² | Rooms, floors, and furniture |
| 1 km² | 1,000,000 m² | Large properties and geographic areas |
| 1 ft² | 0.09290304 m² | Flooring and property measurements |
| 1 in² | 0.00064516 m² | Small objects and manufactured parts |
| 1 yd² | 0.83612736 m² | Carpets, fabric, and landscaping |
| 1 acre | 4,046.8564224 m² | Land and property |
| 1 hectare | 10,000 m² | Agriculture and large land areas |
How to calculate the area of a rectangle
You only need two measurements to find the area of a rectangle. Follow these steps for a manual calculation or use the calculator above.
1. Measure the length
Measure one of the longer sides. Record the measurement and its unit, such as meters, centimeters, or feet.
2. Measure the width
Measure a side perpendicular to the length. Convert the measurements to compatible units before multiplying.
3. Multiply the values
Multiply length by width. If both dimensions are in meters, the answer is in square meters.
Example: 8 m × 3 m = 24 m²
A rectangle measuring 8 meters long and 3 meters wide has an area of 24 square meters.
Where rectangle area calculations are useful
Home renovation
Estimate the surface area of a floor, ceiling, wall, countertop, or rectangular room before purchasing materials.
Construction
Calculate the surface of rectangular slabs, panels, boards, and other building components.
Gardening and land
Estimate the area of rectangular lawns, garden beds, plots, and planting spaces.
Education
Practice geometry, multiplication, measurement conversions, and the relationship between area and perimeter.
Interior design
Estimate flooring, rug, wallpaper, or panel requirements using rectangular measurements.
Manufacturing
Calculate the surface area of flat rectangular sheets, plates, labels, and other materials.
Frequently asked questions
What is the formula for the area of a rectangle?
The formula is A = l × w, where A is the area, l is the length, and w is the width. Multiply the two side measurements to find the surface area inside the rectangle.
How do I calculate the perimeter of a rectangle?
Use P = 2(l + w). Add the length and width and multiply the result by two. For a rectangle that is 10 meters long and 5 meters wide, the perimeter is 30 meters.
How do I calculate a rectangle's diagonal?
Use the Pythagorean theorem: d = √(l² + w²). Square the length and width, add the squares, and take the square root of the sum.
Can length and width use different units?
Yes. This calculator lets you select a separate unit for each measurement. It converts both dimensions to a common unit before calculating area, perimeter, and diagonal.
Why is area measured in square units?
Area measures a two-dimensional surface. Multiplying two lengths multiplies their units too, so meters multiplied by meters gives square meters (m²), while centimeters multiplied by centimeters gives square centimeters (cm²).
What is the difference between area and perimeter?
Area measures the surface enclosed by the rectangle, while perimeter measures the total distance around its boundary. Area is expressed in square units; perimeter is expressed in linear units.
Can a square be calculated with this tool?
Yes. A square is a rectangle with equal length and width. Enter the same measurement in both fields to calculate its area, perimeter, and diagonal.
How accurate are the results?
The calculator uses standard mathematical formulas and unit conversion factors. You can choose the number of decimal places displayed. Displayed rounding does not change the underlying calculation.
Are my measurements uploaded or stored?
The calculations run in your browser using JavaScript. The calculator does not need to send your measurements to a server to calculate the results.
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