### Calculation

Enter a value to any field - the others are calculated themselves. If you change a value in any field, the others are automatically recalculated.
For decimals you can enter either points or commas
as decimal marks (but only one decimal point in a value).

 Radius r = m Diameter d = m Circumference C = m Area A = m² round to 6 digits nm µm mm cm dm m km

The result will be in the units that you enter into the fields.
For example: if you enter millimeters, calculation will be also in millimeters.

If appears an error NaN, check whether you enter to the field
a correct value, ie. without any letters and other characters.

### Formula

 Diameter d = 2 × r [m] Circumference C = π × d = 2 × π × r [m] Area of circle A = π × d²/4 = π × r² [m²] d … diameter = 2 × radius

r … radius = ½ of diameter

S … center of circle

Other formulas for calculating individual parameters, such as side of square, to which a circle is exscribed or inscribed, you will find on a online page calculation of square.

### Calculation of circle online

How can you find this page? It does not matter whether you use a Google or Bing. In the search box, type whatever you think is related to the circle.

Disk (mathematics) is the region in a plane enclosed by a circle.

Here you can find calculation perimeter of circle, circumference or calculation area of circle and disc, length of disc formula. Diameter from circumference, formula of diameter, area of disc from circumference. Function for perimeter of disc online. Formula for calculation of circle and for diameter, converter calculator. 