IF condition (calculating slabs)

What about less than 7 hours?

You could use VLOOKUP for this, using a range lookup (i.e. the fourth setting = TRUE), based on your hour column

Something like =VLOOKUP(HOUR([your time e.g. 9:20]),[slab data table],2,TRUE)

Where slab data table is your list of hours and associated slabs
7 - A
8 - B
etc...

Try:

<b>Excel 2007</b><table cellpadding="2.5px" rules="all" style=";background-color: #FFFFFF;border: 1px solid;border-collapse: collapse; border-color: #A6AAB6"><colgroup><col width="25px" style="background-color: #E0E0F0" /><col /><col /><col /><col /><col /></colgroup><thead><tr style=" background-color: #E0E0F0;text-align: center;color: #161120"><th></th><th>A</th><th>B</th><th>C</th><th>D</th><th>E</th></tr></thead><tbody><tr ><td style="color: #161120;text-align: center;">1</td><td style=";">aaa</td><td style="text-align: right;;">10:16 AM</td><td style="text-align: right;;">7:36 PM</td><td style="text-align: right;;">9:20</td><td style=";">C</td></tr><tr ><td style="color: #161120;text-align: center;">2</td><td style=";">bbb</td><td style="text-align: right;;">11:21 AM</td><td style="text-align: right;;">8:37 PM</td><td style="text-align: right;;">9:16</td><td style=";">C</td></tr></tbody></table><p style="width:3.6em;font-weight:bold;margin:0;padding:0.2em 0.6em 0.2em 0.5em;border: 1px solid #A6AAB6;border-top:none;text-align: center;background-color: #E0E0F0;color: #161120">Sheet1</p><br /><br /><table width="85%" cellpadding="2.5px" rules="all" style=";border: 2px solid black;border-collapse:collapse;padding: 0.4em;background-color: #FFFFFF" ><tr><td style="padding:6px" ><b>Worksheet Formulas</b><table cellpadding="2.5px" width="100%" rules="all" style="border: 1px solid;text-align:center;background-color: #FFFFFF;border-collapse: collapse; border-color: #A6AAB6"><thead><tr style=" background-color: #E0E0F0;color: #161120"><th width="10px">Cell</th><th style="text-align:left;padding-left:5px;">Formula</th></tr></thead><tbody><tr><th width="10px" style=" background-color: #E0E0F0;color: #161120">D1</th><td style="text-align:left">=(<font color="Blue">C1-B1</font>)</td></tr><tr><th width="10px" style=" background-color: #E0E0F0;color: #161120">E1</th><td style="text-align:left">=LOOKUP(<font color="Blue">D1*24,{7,8,9,10},{"A","B","C","D"}</font>)</td></tr></tbody></table></td></tr></table><br />

Overlap?

Should 7 -8, 8 - 9 etc be

7 - 7:59, 8 -8:59

Also, what output for less than 7 hours or more than 11?

Consider:

=LOOKUP(HOUR(A1),{0,7,8,9,10,11},{"","A","B","C","D",""})

Does this give anything like the results you're after?

Two alternatives:
E2 and copy down using lookup table.
F2 and copy down without the need for a lookup table.

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