Calculate Age in Months

**Tim Hardison** · 11-09-2009, 07:09 PM

I need to be able to calculate age in months, and round whatever remainder to the middle of the month (.5). I am calculating z-scores and percentiles for in a childhood obesity project. The DoB and Date of measurements must be converted to read anything from 142.0 to 142.9 as 142.5. This value will be used to look up the the appropriate LMS (Box Cox, Median, and Standard Deviation) in another excel table. I have to be able to compute age in months so 142.5, 143.5, 144.5, 144.5 etc. It is just not rounding off to the nearest half month. Can anyone help?

**shg** · 11-09-2009, 07:17 PM

If A1 contains DOB and B1 the as-of date, then =DATEDIF(A1, B1, "m") + 0.5

**Tim Hardison** · 11-09-2009, 07:28 PM

came back with a #NUM! displayed.

**shg** · 11-09-2009, 07:30 PM

A1 has to be the earlier of the two dates.

An alternative: =INT(ABS((B1-A1))/30.44) + 0.5

**teylyn** · 11-09-2009, 07:31 PM

Tim, check that your cells contain real dates!

**Tim Hardison** · 11-09-2009, 07:37 PM

I reversed the dates and got 5/27/1900. I got a similar answer to this a couple days ago, and went to Format, Cells, Clicked on the Numbers tab and clicked on Number. It the computed it to 142.00. I am going to try to format it to a number and see will it at the .5

**Tim Hardison** · 11-09-2009, 07:40 PM

It did it!!! Sorry I had a double posting. I have never done one of these forum things. Thanks a bunch. I think I am going to ask another question. How do I mark this thing as solved?