Circular Ring Area Calculator (A = πw(R+r))

The calculator applies the exact formula A = π(R² − r²) = π·w·(R + r). Worked example: R = 5 cm, r = 3 cm → A = 50.27 cm². Keep every input in one unit system and the result follows in square units (m², ft², cm²); full precision is kept until the final rounding. All side lengths must share one unit or the area comes out scaled wrongly.

1. 1

   Enter the measurements

   Type the values required by the formula for circular ring area.

2. 2

   Check the units

   One unit system throughout — cm, m, ft or in.

3. 3

   Read the result

   The calculator substitutes, evaluates and rounds only at the end.

• 1

  Area scales with the square of linear dimensions

• 2

  1 m² = 10.764 ft² for quick conversion

• 3

  Sketch and label the shape before entering values

• Unit mix-ups between cm² and m² (factor 10,000)

• Using a slanted length as a perpendicular height

• Treating an irregular shape as regular