2025• About This Calculator This calculator determines the area of a circle using either the radius or the diameter. You may also enter a custom value for π， Circle Area Calculator Last updated: July 2。
input a custom value for π if you are using an approximation like 3.14. Click "Calculate" to find the area of the circle. Area = π × r² or Area = π × (d ÷ 2)² Frequently Asked Questions Which is more accurate， leaving it blank uses 3.14159 by default. ， radius or diameter? Both provide the same result. The calculator will automatically convert one to the other and use it to compute the area. When should I use a custom value for π? Custom π values are useful for school exercises or exams where π is specified as 3.14 or other simplified values. For precise results， or use the default value of 3.14159. How It Works Enter either the radius or the diameter of the circle. The other value will be auto-filled for your convenience. Optionally，。