OhMyCalc

Area Calculator

Calculate the area of common geometric shapes: triangle, circle, rectangle, square, trapezoid, parallelogram, rhombus, and ellipse. Choose a unit and see the formula.

Formula: A = a × b

How to Use the Area Calculator

  1. Enter the required dimensions (length, width, radius, height, etc.).
  2. The area, volume, or other geometric value is computed instantly.
  3. Review the result along with the formula used.
  4. Adjust dimensions to compare different scenarios.

使用例

計算式

Triangle: A = ½bh. Circle: A = πr². Rectangle: A = ab. Square: A = a². Trapezoid: A = ½(a+b)h. Parallelogram: A = bh. Rhombus: A = ½d₁d₂. Ellipse: A = πab.

よくある質問

How do I calculate the area of a triangle?
Multiply the base by the height and divide by 2: A = ½ × base × height. The height must be perpendicular to the chosen base.
What is the area of a circle?
A = π × r², where r is the radius. For example, a circle with radius 5 has area π × 25 ≈ 78.54 square units.
What is the difference between a rhombus and a parallelogram?
A rhombus has all four sides equal in length, while a parallelogram only requires opposite sides to be equal. A rhombus is a special case of a parallelogram.
How do I choose the right unit for area?
Use the same unit as your measurements, squared. If you measure in centimeters, the area is in cm². Common choices: mm², cm², m², km² for metric; in², ft² for imperial.