Rectangle Area Calculator

Fill in any two of length, height and area, then click Calculate. The tool uses Area = Length × Height to compute the remaining value automatically.

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Please fill exactly two of length, height and area, leave one blank, and the calculator will find the missing value.
Result
Rectangle Area Diagram
矩形面积计算公式: \(S = l \times h\)
A
Find Length
Fill fields:
Height Area
and leave blank:
Length
B
Find Height
Fill fields:
Length Area
and leave blank:
Height
C
Find Area
Fill fields:
Length Height
and leave blank:
Area

About Rectangle Area Calculator

This calculator is based on the rectangle area formula: Area = Length × Height. Knowing any two of these lets you solve for the third.

If you know length and height, Area = Length × Height. If you know area and length, Height = Area ÷ Length. If you know area and height, Length = Area ÷ Height.

Rectangle area is widely used in floor planning, land measurement, graphic design, packaging and many other scenarios. This tool lets you perform these conversions quickly.

Make sure all values are greater than 0 and use consistent units (for example, all in meters, centimeters or millimeters) so the result remains meaningful.

Quiz: Test Your Rectangle Area Knowledge

1. What is the basic formula for the area of a rectangle?

Area = Length × Height.

2. If a rectangle is 5 m long and 3 m high, what is the area?

Area = 5 × 3 = 15 m².

3. If the area is 20 m² and the height is 4 m, what is the length?

Length = Area ÷ Height = 20 ÷ 4 = 5 m.

4. Why must the units of length, height and area be consistent?

Only consistent units produce meaningful area values; mixing units leads to wrong results.

5. How is a square related to a rectangle in area calculation?

A square is a special rectangle with equal sides, so Area = side × side.

6. How is rectangle area useful when installing flooring?

You can compute the floor area from room length and width to estimate material quantities.

7. Can this tool be used if you only know one side and the diagonal?

No. This tool relies on Area = Length × Height and needs any two among length, height and area.

8. Can you enter decimal values for area, length or height?

Yes. All three fields accept decimals for more precise calculations.

9. Who can benefit from this rectangle area calculator?

Students, teachers, engineers, designers and anyone who needs rectangle area conversions.

10. Why can length or height not be negative in this calculator?

Length and height represent physical dimensions and must be positive; negative values have no geometric meaning.

Rectangle Area Calculator

This tool helps you find the third value when any two of length, height and area of a rectangle are known. Useful for learning, design and daily calculations.

Scan the QR code to use this tool on mobile.