In this example, we’ll learn How to calculate area and perimeter of a rectangle in C# WinForm. To find the area of a rectangle or a square you need to multiply the length and the width of a rectangle.

**Form Design:**

**Source Code:**

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private void button1_Click(object sender, EventArgs e) { int width = Convert.ToInt32(txtWidth.Text); int length = Convert.ToInt32(txtLength.Text); int area = width * length; int perimeter = (width + length) * 2; lblPerimeter.Text = "Perimeter : " + perimeter; lblArea.Text = "Area : " + area; } |

**Output:**