# Greek Small Letter Tau

τ
Symbol Format Data
τ Code Point
U+03C4
TeX
\tau
SVG

## Usage

The Greek small letter τ (tau) is used in math as the circle constant to represent a full rotation around a circle in radians. The value of is approximately and can be calculated by dividing any circle’s circumference by its radius. Typically, the symbol appears in an expression like this:

This expression is a formula for the area of a circle. In plain language, this expression can be read as: the area of the circle is equal to one-half multiplied by the constant (tau) multiplied by the radius of the circle squared.

## Related

The capital Greek letter Τ (capital tau).