The height (ordinate) of a normal curve is defined as:

where μ is the mean and σ is the standard deviation, π is the constant 3.14159, and e is the base of natural logarithms and is equal to 2.718282.

x can take on any value from -infinity to +infinity.

f(x) is very close to 0 if x is more than three standard deviations from the mean (less than -3 or greater than +3).