Counting Distinct Entries In A Range

Q. Can I write a formula that returns the number of distinct entries in a range?

First, let's clarify the question. We're hunting for a formula that, given the range that contains the values 100, 99, 98, 100, 98, 100, 98, would return 3. In other words, this range contains three different values, some of them repeated.

This type of counting requires an array formula. The formula below, for example, counts the number of distinct entries in the range A1:D100.

=SUM(1/COUNTIF(A1:D100, A1:D100))

When you enter this formula, you must press Ctrl-Shift-Enter. Pressing only Enter will give you the wrong result. Excel will place brackets around the formula to remind you that you've created an array formula.

The preceding formula works fine in many cases, but it will return an error if the range contains any blank cells. The formula below (also an array formula, so input it with Ctrl-Shift-Enter) is more complex, but it will handle a range that contains a blank cell.

=SUM(IF(COUNTIF(A1:D100,A1:D100)=0, "", 1/COUNTIF(A1:D100,A1:D100)))