This is a quick trick, but a real timesaver. Every day I encounter the situation where I have a filtered list of data and I want to sum up one of the columns. A simple example can be seen in the screen grab below, where I have some fictional officers across four platoons with their monthly ticket totals.

Your first instinct might be to use =SUM(D4:D23) as I did in cell D2 and that will calculate the sum for all the rows of data. The problems arise when you want to calculate the sum for a subset of the records, for example, the sum of tickets for just Platoon 1.

Whoops, even though I filtered the Unit column down to just Platoon 1, the sum remains the same.

To the rescue is the function SUBTOTAL(). Instead of SUM, in the following screen grab I’ve used the formula =SUBTOTAL(9,D4:D23).

As you can see, the value is the same as SUM. The magic happens when I start using the filters.

The SUBTOTAL updates itself depending on what records are visible in the range. Perfect.

You may be asking “Why the 9?” and that’s because SUBTOTAL can handle a variety of functions, not just summing. The function to be used is specified by the function_num parameter in the first slot, and 9 corresponds with SUM. You could just as well use 1 for AVERAGE or 2 for COUNT, etc. The following screen grab shows the options that are available.

My advice? Get used to always using SUBTOTAL. If you filter data sets as often as I do, it’ll change your life.