I want to automatically increase 15 minute interval to the cells once I enter in one cell in the Microsoft Excel (.xls)file.

For Example:

In cell D11 I enter manually 3:00(i.e format  h:mm),
then automatically data should come to other cells i.e(E11, F11, G11, H11, I11, J11, K11, L11, M11, N11, O11) be 3:15, 3:30, 3:45, 4:00, 4:15, 4:30, 4:45, 5:00, 5:15, 5:30, 5:45

This file has four sheets, We have to enter only 3:00 in cell D11 in first sheet then automatically it should display of 15 minute interval data to other cells(as I have mentioned above i.e E11 to O11) of the all four sheets.

Note: User can enter either 3:00 or 4:00 or anything, but it should take 15 minute interval

OK, for this you need a excel manipulator.

So google php excel and you should come up with a few. Then you have to install it and configure the php .ini file.

But beware! If you plan to use this online some web hosting companies make it difficult for you to install php modules, so first find this out.

Now the logic for your question is pretty simple.

Clearly just increment the minutes by 15, but then increment the hour when it reaches 60.

Alternatively, I guess you could use the php date/time class but I think it's overkill for logic so simple.