Automatically deduct lunch breaks

Before asking I tried doing some research on possible formulas but I guess I am not getting it. also I have a basic/intermediate knowledge of excel. and I only have about two weeks on excel2013 previously on 2007.

So question is I need a formula to automatically deduct 30min of lunch if they worked 8hrs or no lunch break if they work 4hrs.

8hrs deduct 30mins
4hrs no lunch

I found the following formula but it is not working:

=(B3-A3)*24-IF((B3-A3)*24>8,1,IF((B3-A3)*24>6,0.5,0))

Cells in A&B are formatted 1:30PM
Cell in C is formatted [h]:mm

In advance, thank you for time and patience.

Here is a snapshot of what I have:

timesheet.jpg

If you have a better and/or simpler formula I will test it!

Hi Popipipo,

Thank you!

Just had to change 1/24 -> 1/48 as it was subtracting 1:00 instead of :30

but now I have another dilemma:

now that I have calculated the total hours per day, the sum of all five days do not add up! :-(

8:00 + 4:00 = 12:00 (but system response is 10:30)

formula =sum()
formatted [h]:mm

timesheet-2.jpg

ok, here it is.

timesheet-test.xlsx

there is only two options

8hrs 30mins
4hrs no lunch

there will be no other times between

Ok, I got the result of 12 on cell M5 as what I wanted

What did you do to cell M5 to produce the correct answer?

AND

why did you change the formula from the original one? the original formula you provided was correct!