While preparing a project plan, I had a strange problem. I wanted to highlight all the project tasks that fall with-in a certain date range. At the lowest level, the problem is like this:
There are 2 ranges of dates (a,b) and (x,y) and I want to know if they overlap (ie at least one date common between a,b and x,y)
The formula for testing such a thing seemed tricky at first. So I drew the conditions on paper to get clarity on what we should test. Evidently, there are 4 ways in dates (a,b) can overlap with dates (x,y) as shown below:
Now, we can test for the overlap condition using a formula like this:
If x is between a and b
or a is between x and y
then overlap
else do not overlap
As you know, there is no formula in excel like isbetween(). So we have to break it up to 2 conditions and an AND() Formula. Finally the formula becomes,
=if(or(and(x>=a,x<=b),and(a>=x,a<=y)),"Overlap","Do not overlap")
Now, it seemed like quite a big formula for testing if 2 ranges of dates overlap.
So, I continued my quest for even shorter formula.
After sometime, I realized that if we test for non-overlap instead of overlap, we can write a shorter formula.
Do not understand? Let me explain.
While there are 4 ways in which (a,b) can overlap with (x,y), there are only two ways in which (a,b) cannot overlap with (x,y). See this to understand:
Now, testing above conditions is very straight forward in excel.
the formula becomes, =if(or(y<a,b<x),"Do not overlap","Overlap")
The formula is much shorter and easy to maintain.
I was able to use it to test if a set of tasks in the project plan are running between given dates (for eg. next week). All is well in the end.
How do you test overlap conditions?
Do you ever have to test overlap conditions? What kind of formulas have you used? Please share your formula tips & tricks using comments.
13 Responses to “Convert fractional Excel time to hours & minutes [Quick tip]”
Hi Purna..
Again a great tip.. Its a great way to convert Fractional Time..
By the way.. Excel has two great and rarely used formula..
=DOLLARFR(7.8,60) and =DOLLARDE(7.48,60)
basically US Account person uses those to convert some currency denomination.. and we can use it to convert Year(i.e 3.11 Year = 3 year 11 month) and Week(6.5 week = 6 week 5 days), in the same manner...
This doesn't work for me. When applying the custom format of [h]:mm to 7.8 I get 187:12
Any ideas why?
@Jason
7.8 in Excel talk means 7.8 days
=7.8*24
=187.2 Hrs
=187 Hrs 12 Mins
If you follow Chandoo's instructions you will see that he divides the 7.8 by 24 to get it to a fraction of a day
Simple, assuming the fractional time is in cell A1,
Use below steps to convert it to hours & minutes:
1. In the target cell, write =A1/24
2. Select the target cell and press CTRL+1 to format it (you can also right click and select format cells)
3. Select Custom from “Number” tab and enter the code [h]:mm
4. Done!
Hi, sorry to point this out but Column C Header is misspelt 'Hours Palyed'
good one
So how do I go the other way and get hours and minutes to fractional time?
If you have 7.5 in cell A1,
- Use int(A1) to get the hours.
- Use mod(A1,1)*60 to get minutes.
If you have 7:30 (formatted as time) in A1
- Use hours(a1) to get hours
- Use minutes(a1) to get minutes.
I had the same issue. You can solve it by changing the format as described above:
Right click cell > Format Cells > (In Number tab) > Custom > Then enter the code [h]:mm
([hh]:mm and [hhh]:mm are nice too if you want to show leading zeros)
Thanks guys, these are the tips I'm looking for.
...dividing the number of minutes elapsed by the percent change is my task - "int" is the key this time
It doesnt work for greater than 24 hours
It returns 1:30 for 25.5 hours. It should have returned 25:30
Ideally I would right function as
=QUOTIENT(A1,1)&":"&MOD(A1,1)*60
Sorry, replied to wrong comment....
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I had the same issue. You can solve it by changing the format as described above:
Right click cell > Format Cells > (In Number tab) > Custom > Then enter the code [h]:mm
([hh]:mm and [hhh]:mm are nice too if you want to show leading zeros)
Clever use of MOD here to extract the decimal part of a number. Divide a number containing a decimal by 1 and return the remainder. Humm. Very clever.
Thanks very much, extremely useful !