How to Get the Normal Density with PHI in Excel

Use PHI to read the height of the bell curve — for size planning, density per unit and comparing how common two values are.

You will learn to

• Read the bell-curve height at a z-score
• Convert the density to real units
• Compare how common two values are

How it works

PHI(z) returns the height of the standard normal bell curve at z — the density, not a probability. =PHI(0) is about 0.399, the peak of the curve, and =PHI(1) is about 0.242. It is the same as NORM.S.DIST(z,FALSE).

Density is useful in its own right: divide PHI((x−mean)/sd) by the SD to get the approximate share of people per unit near x, and divide two densities to see how many times more common one value is than another. That is handy for sizing ranges and for drawing bell-curve charts.

=PHI(1)