This formula uses the named ranges "dates" (B5:B25) and "durations" (D5:D25). Durations column D are in minutes, calculated by subtracting the date opened from date closed.
The AVERAGEIFS function is designed to average ranges based on multiple criteria. In this case, we configure AVERAGEIFS to average durations by month using two criteria: (1) matching dates greater than or equal to the first day of the month, (2) matching dates less than or equal to the last day of the month.
To bracket dates by month, we use a simple trick to make things easier: In column F, instead of typing month names ("Jan", "Feb", Mar", etc.) we add we add actual dates for the first of each month (1/1/2016, 2/1/2016, 3/1/2016, etc.),. Then, we use the custom date format ("mmm") to display the month names.
This makes it a lot easier to build the criteria we need for AVERAGEIFS using values in column F. To match dates greater than or equal to the first of the month, we use:
To match dates less than or equal to the last day of the month, we use:
We get the EOMONTH to return the last day of the same month by supplying zero for the months argument.
Note: concatenation with an ampersand (&) is necessary when building criteria based on a cell reference.
Pivot Table solution
A pivot table is an excellent solution when you need to summarize or average data by year, month, quarter, and so on, because pivot tables provide controls for grouping dates automatically. For a side-by-side comparison of formulas vs. pivot tables, see this video: Why pivot tables.
The first argument for SUMIFs is always the range to sum ("sum_range"), and criteria are supplied as one or more range / criteria pairs. In this example, the sum range is a named range called "amount" (E3:E2931), and the criteria are supplied in two...
The SUMIFS function can sum values in ranges based on multiple criteria. In this case, we configure SUMIFS to sum amounts by month using two criteria: one to match dates greater than or equal to the first day of the month, one to match dates less...
The AVERAGEIFS function can average ranges based on multiple criteria. In this case, we configure AVERAGEIFS to average amounts by month using two criteria: (1) match dates greater than or equal to the first day of the month, (2) match dates less...
The Excel AVERAGEIFS function calculates the average of numbers in a range that meet one or more criteria. The criteria used for AVERAGEIFS can include logical operators (>,,=) and wildcards (*,?) for partial matching....
The Excel EOMONTH function returns the last day of the month, n months in the past or future. You can use EDATE to calculate expiration dates, due dates, and other dates that need to land on the last day of a month. Use a positive value for...
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