How do I use the Rectangle Area Calculator?
Enter your values in the fields and the result updates instantly as you type.
Rectangle Area Calculator
Compute area and perimeter of a rectangle. Enter your values, review the formula, and use the worked result as a quick check for everyday planning.
Rectangle Area Calculator
Compute area and perimeter of a rectangle.
e.g., cm, m, ft, in
e.g., cm, m, ft, in
Results
Area
40 sq units
Perimeter
26 units
Formula: Area = length * width, Perimeter = 2 * (length + width)
Rectangle Area and Perimeter Calculator
Find the area and perimeter of any rectangle by entering length and width. Used for flooring, painting, fencing, landscaping, and any rectangular surface measurement.
Formula
Area = Length × Width. Perimeter = 2 × (Length + Width). Input any consistent unit — the results are in square units (area) and units (perimeter) of whatever measure you use.
Worked example
Length 8, width 5: area = 40 sq units, perimeter = 26 units. A 12 × 9 rectangle: area = 108, perimeter = 42.
Practical guidance
Finding missing dimensions
If you know the area and one side, divide area by the known side to find the other. A room with 60 m² area and 10 m length has 6 m width. This calculator works forward; use algebra for reverse calculations.
Unit consistency matters
If your length is in meters and width in centimeters, convert both to the same unit first. A 5 m × 200 cm rectangle: convert 200 cm to 2 m, then area = 10 m². Mixing units without conversion produces meaningless results.
Frequently asked questions
What formula does this calculator use?
Area = length * width, Perimeter = 2 * (length + width)
Can I use decimal values?
Yes. Decimal inputs are supported for most calculators. Integer-based tools use rounded integer values where appropriate.
Is this calculator free?
Yes. CalcuNimble calculators are free and optimized for fast everyday use.