Square in a Circle Calculator

Your details

Choose the geometry problem you want to solve.
The radius of the circle (half the diameter).
cm
Result
14.1421cm

The key dimension for the chosen geometry mode

Square side length14.1421cm
Square diagonal20cm
Square area200cm²
Circle radius10cm
Circle diameter20cm
Circle area314.1593cm²
Coverage ratio0.64%
Circle circumference62.8319cm
Square perimeter56.5685cm

A circle of radius 10.00cm fits a square with side 14.1421cm.

  • The square's diagonal equals the circle's diameter (20.0000cm), which is what makes this the largest possible inscribed square.
  • The square covers 63.66% of the circle's area (always 2/π ≈ 63.66% for any inscribed square).
  • The square's area is 200.0000cm², exactly twice the square of the radius (2r²).

Next stepFor construction work, mark the diameter twice at 90 degrees to find all four corners of the inscribed square.

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