Rectangle Calculator — Area, Perimeter & Diagonal
Use this calculator to quickly compute the area, perimeter, and diagonal length of a rectangle. Enter the length and width, and results will be calculated automatically. This tool is useful for geometry homework, construction planning, design, and any task where rectangle dimensions are involved. Whether you're a student, a professional, or simply curious about geometric calculations, our rectangle calculator is designed to simplify the process for you.
Formulas for Rectangle Calculations
Basic Formulas
Area = Length × WidthPerimeter = 2 × (Length + Width)Diagonal = √(Length² + Width²)All formulas assume both length and width are in the same units. The area will be in square units (units²), while perimeter and diagonal are in linear units.
Example of Rectangle Calculations
How to Use the Calculator
Suppose a rectangle has length = 10 and width = 5.
- Area = 10 × 5 = 50 units²
- Perimeter = 2 × (10 + 5) = 30 units
- Diagonal = √(10² + 5²) = √125 ≈ 11.18034 units
How to Use the Rectangle Calculator
- Enter the length in the first field.
- Enter the width in the second field.
- Results update automatically — no need to press calculate.
- Optional: Toggle charts to visualize area, perimeter, and diagonal comparisons.
Frequently Asked Questions About Rectangles
Do length and width need to use the same units?
Yes. Ensure both values are in the same units (for example, both in meters) so that area and diagonal calculations are correct.
What units are the results shown in?
Area is shown in square units (units²). Perimeter and diagonal are shown in linear units (units). If you enter meters, the area will be in square meters (m²) and others in meters (m).
Can I use decimals?
Yes. You can enter decimal values (for example 2.5). The calculator supports fractional dimensions and will display results with up to 6 decimal places.
Helpful Tips for Working with Rectangles
- For construction or cutting materials, round up the area when ordering supplies to account for waste.
- Use the diagonal length to check if a rectangle is right-angled when comparing to measured diagonals on-site.
Use Cases for the Rectangle Calculator
This rectangle calculator is not only useful for students but also for various professionals. Architects and builders can use it to estimate the materials required for construction. Graphic designers may need to calculate the area of rectangular images, while event planners can determine space requirements for layout designs. By leveraging this tool, users from different backgrounds can enhance their precision and efficiency in tasks involving rectangles.