Find the area of any circle in one step by entering its radius. The area of a circle equals pi times the radius squared, written as A equals pi r squared, and this calculator applies that formula instantly as you type. If you only know the diameter, remember that the radius is half of the diameter, so a value of 10 for the diameter means a radius of 5. Circle area comes up constantly in real work: sizing a round table, estimating paint for a circular wall, planning a garden bed, or solving homework problems. The result appears in the same units squared that you entered, so a radius in centimeters returns square centimeters. Everything runs locally in your browser with no rounding surprises, and you can copy the result with a single click.
The area is pi times the radius squared, so a radius of 3 gives an area of about 28.27.
Yes. The tool accepts either, and it halves the diameter to get the radius before applying the formula.
The area is in the square of whatever unit you enter, so a radius in centimeters gives an area in square centimeters.
Find the area of any circle in one step by entering its radius. The area of a circle equals pi times the radius squared, written as A equals pi r squared, and this calculator applies that formula instantly as you type.
Yes. Circle Area Calculator is completely free, with no sign-up and no usage limits.
Yes. Circle Area Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Circle Area Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.