Explanation
This formula uses the COUNTA function to count values in a range. COUNTA counts both numbers and text to so works well with mixed data.
The range B4:B8 contains 5 values, so COUNTA returns 5. The number 5 corresponds to the last row (last relative position) of data in the range B4:B100.
Note: This approach will fail if the range contains blank/empty cells. This formula based on the LOOKUP function can handle empty cells in the data.
Dynamic range
You can use this formula to create a dynamic range with other functions like INDEX and OFFSET. See links below for examples and explanation:
- Dynamic range with INDEX and COUNTA
- Dynamic range with OFFSET and COUNTA
Inspiration for this article came from Mike Girvin’s excellent book Control + Shift + Enter .
Explanation
When building advanced formulas that use dynamic ranges, it’s often necessary to figure out the last location of data in a list. Depending on the data, this could be the last row with data, the last column with data, or the intersection of both. Note: we want the last relative position inside a given range , not the row number on the worksheet. The screen below shows the idea:
This formula uses the MATCH function in approximate match mode to locate the last numeric value in a range. Approximate match enabled by setting by the 3rd argument in MATCH to 1, or omitting this argument, which defaults to 1.
The lookup value is a so-called “big number” (sometimes abbreviated “bignum”) which is intentionally larger than any value that will appear in the range.
The result is that MATCH will “step back” to the last numeric value in the range, and return that position.
Note: this approach works fine with empty cells in the range, but is not reliable with mixed data that includes both numbers and text.
About bignum
The biggest number Excel can handle is 9.99999999999999E+307.
When using MATCH this way, you can use any large number that is guaranteed to be larger than any value in the range, for example:
=MATCH(1E+06,range) // 1 million
=MATCH(1E+09,range) // 1 billion
=MATCH(1E+12,range) // 1 trillion
The advantage to using 9.99E+307 or similar, is that it’s (1) a huge number and (2) recognizable as a placeholder for a “big number”. You’ll see it used in various advanced Excel formulas.
Dynamic range
You can use this formula to create a dynamic range with other functions like INDEX and OFFSET. See links below for examples and explanation:
- Dynamic range with INDEX and COUNTA
- Dynamic range with OFFSET and COUNTA
Inspiration for this article came from Mike Girvin’s excellent book Control + Shift + Enter , where Mike explains the concept of “last relative position”.
