Explanation
In this example, the goal is to count cells in the range D5:D15 that contain "red" or "blue". For convenience, the D5:D15 is named color. Counting cells equal to this OR that is more complicated than it first appears because there is no built-in function for counting with OR logic. The COUNTIFS function will allow multiple conditions, but all conditions are joined with AND logic. The article below explains several options.
COUNTIF + COUNTIF
A simple, manual way to count with OR is to use the COUNTIF function more than once:
=COUNTIF(color,"red") + COUNTIF(color,"blue")
In both cases, the range argument inside COUNTIF is color (D5:D15). However, criteria is "red" in the first COUNTIF and "blue" in the second. The first COUNTIF returns 4 and the second COUNTIF returns 3, so the final result is 7. This formula works fine, but it is somewhat redundant.
COUNTIF with array constant
Another way to configure COUNTIF is with an array constant that contains more than one value to use for criteria. This is the method used in the example shown above:
=SUM(COUNTIF(color,{"red","blue"}))
Inside the SUM function, the COUNTIF function is given color (D5:D16) for range and {"red","blue"} for criteria:
COUNTIF(color,{"red","blue"}) // returns {4,3}
This causes the COUNTIF function to return two counts: one for "red" and one for "blue". These counts are returned directly to the SUM function in a single array:
=SUM({4,3}) // returns 7
And SUM returns 7 as the result. In other words, COUNTIF returns multiple counts to SUM, and SUM returns a final result. This is an example of nesting one formula inside another.
For more complicated scenarios, see: COUNTIFS with multiple criteria and or logic
SUMPRODUCT function
Another way to solve this problem is with the SUMPRODUCT function like this:
=SUMPRODUCT((D5:D15="red")+(D5:D15="blue"))
This is an example of using Boolean logic. Inside SUMPRODUCT there are two expressions joined by the addition (+) operator. Because color contains 11 values, each expression creates an array with 11 TRUE and FALSE values:
=SUMPRODUCT({TRUE;TRUE;FALSE;FALSE;FALSE;FALSE;TRUE;FALSE;FALSE;TRUE;FALSE}+{FALSE;FALSE;TRUE;FALSE;TRUE;FALSE;FALSE;FALSE;TRUE;FALSE;FALSE})
In the first array, the TRUE values correspond to cells that contain "red". In the second array, the TRUE values correspond to cells that contain "blue". When the two arrays are added together, the math operation converts the TRUE and FALSE values to 1s and 0s:
=SUMPRODUCT({1;1;1;0;1;0;1;0;1;1;0})
With just one array to process SUMPRODUCT sums the items in the array and returns 7 as a result. Another way to configure SUMPRODUCT is like this:
=SUMPRODUCT(--(D5:D15={"red","blue"}))
In this formula, the expression:
D5:D15={"red","blue"})
Returns a single array with 11 rows and 2 columns. The double negative coerces the TRUE and FALSE values to 1s and 0s:
=SUMPRODUCT({1,0;1,0;0,1;0,0;0,1;0,0;1,0;0,0;0,1;1,0;0,0})
And SUMPRODUCT again returns 7 as a final result.
For more complex scenarios see: SUMPRODUCT with multiple criteria and OR logic and Count cells equal to one of many things.
Double-counting risk
When counting with OR logic, be aware of the risk of double-counting. In this particular example, the values "red" and "blue" are values in the same field, so there is no danger in double-counting. However, if you are counting records where one field is "red" OR another field is "blue", take care not to double-count, since both can be true at the same time in the same record.