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Circle & Sphere calculations in Excel using Pi ๐œ‹

Use these handy Excel formulas for circle and sphere calculations! Whether they’re a distant memory from school days or a recent discovery, you can easily compute them using Pi ฯ€, or as Excel dubs it, Pi().

Many formulas rely on Pi ๐œ‹ so Excel has a simple function Pi() which inserts Pi to 14 decimal places.ย  Thatโ€™s accurate enough for almost any purpose including calculating planetary motions and saves everyone typing 3.14159265358979 over and over again.

Circle formulas in Excel

Formulas to work out the Circumference, Area, Arc Length and Arc Area of a circle.

Copy any of these formulas into Excel, replace the names with cell references/names and youโ€™re good to go!

CircleExcel Formula
CIRCUMFERENCE from radiusฯ€r2=PI()*Radius*2
CIRCUMFERENCE from diameter=PI()*Diameter
DIAMETER from circumference=Circumference/PI()
RADIUS from circumference=Radius/PI()*2
AREA from radius=PI()*Radius^2
AREA from diameter=PI()*(Diameter/2)^2
AREA from circumference=(Circumference/PI()/2)^2*PI()
ARC LENGTH from radius and angle in degrees=2*PI()*Radius*(AngleDegrees/360)
ARC AREA from radius and angle in degrees=(PI()*Radius^2)*(AngleDegrees/360)

Sphere formulas in Excel

For a sphere or ball, here’s the Excel formulas for Surface Area and Volume.

SphereExcel Formula
SURFACE AREA from diameter=PI()*(Diameter^2)
SURFACE AREA from radius=PI()*(Radius*2)^2
VOLUME from diameter=PI()*Diameter^3/6
VOLUME from radius=PI()*(Radius*2)^3/6

Earth, Moon and Sun calcs in Excel

Here’s the sphere formulas in practice for the surface area and volume of our planet and some near neighbors.

Pedantic Note: all the above assumes the Earth, Moon and Sun are completely spherical. The Earth and its moon are both oblate spheroids (they bulge at the equator due to axis spin). The Sun also has a slight bulge but it’s unexpectedly small.

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