# Average Days between a range of dates?

1. ## Average Days between a range of dates?

Is there a way to calculate the average days between a column of dates?

Basically, I've got a sheet that contains a table of entries, and each entry gets a date stamp in the first column. I would like to have the sheet display the average time, in days, between entries. Is this possible?

~cp  Register To Reply

2. Hi,

Start date in A1, End date in B1, then in C1

=(B1-A1)/2 format to General  Register To Reply

3. So there's no way to just average the difference between a single column of dates?

ie, The start date would be the first row of the column, and the next date would be the end date for the first range, and the start of the next, then the following row would be the end date of that range, and the start of the next, ad infinitum. Does that make any sense? I don't want to have to enter the same date in two columns =\  Register To Reply

4. Hi,

To get an average between two dates you need to take one from the other, if all the dates are in the same column how do you know which is the start date and which is the end date?

Does this picture help, if you put your formula in C2

=(B2-B1)/2 then select C1:C2 and drag down the averages fill in automatically  Register To Reply

5. So you are looking for the overall average length of each range within a single column where the final date of one range = the start date of the next?

It should be doable with array formulas but haven't been able to figure it out.

ChemistB  Register To Reply

6. Originally Posted by oldchippy
Hi,

To get an average between two dates you need to take one from the other, if all the dates are in the same column how do you know which is the start date and which is the end date?

Does this picture help, if you put your formula in C2

=(B2-B1)/2 then select C1:C2 and drag down the averages fill in automatically

Nice, that's perfect. I tried something similar earlier, but must have screwed it up. Thanks for your help though, that's more or less exactly what I was looking for. Of course it had to be millions of times simpler than I'd expected. Go figure!

Thanks again!
~c  Register To Reply

7. Glad it helped - thanks for the feedback  Register To Reply

8. Sorry, perhaps I didn't understand this.....

Did you want the average of all the differences, A2-A1, A3-A2, A4-A3 etc?
Assuming that the dates are all in ascending order you could calculate that with the difference betwen last and first dates divided by the number of dates less 1, i.e.

=(MAX(A:A)-MIN(A:A))/(COUNT(A:A)-1)  Register To Reply