How to calculate average of number of months and days

**Melissagata** · 06-15-2020, 01:16 PM

Hi, I have data in number of months and days such as
6 months
8 months 13 days
20 days
11 months

I would like to know how to calculate average of these datas and what formula should I use.

Thank you so much.

**oeldere** · 06-15-2020, 01:33 PM

@Melissagata

Welcome to the excel forum.

Count the days in the months and after that take the average of that.

All months are 30 days? Each month has it's own days?

What should be the answer?

Fast answers need clear examples. Post a small Excel sheet (not a picture) showing realistic & representative sample data WITHOUT confidential information (10-20 rows, not thousands...) and some manually calculated results. Just before posting, scroll down to GO ADVANCED, click, and then scroll down to MANAGE ATTACHMENTS and click again. Now follow the instructions at the top of that screen.

**GeoffW283** · 06-23-2020, 02:24 AM

Pending the additional data requested by oeldere, here is a guess at what you might be looking for. Refer to the attached image below. I have assumed a constant 365/12 days per month in cell G1
Also assumed is that your month and day values are in separate columns B and C.
Now, given the above, in column D compute each duration in days, so in D2 copied down to D5:

Formula:

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Now in D6 calculate the average duration in days as:

Formula:

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Finally express the average as months and days. In B6 (months):

Formula:

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And in C6 (days):

Formula:

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The attached workbook implements the above.
Hopefully this is close to what you are looking for. If not then please provide additional data as requested by oeldere.