title: SUM data according to dates in Excel
body: <p>My problem is the following...</p>
  
  <p>I have a little aeroplane and I need to track the hours. I have to track the hours by sectors and not the total of the day (that's why sometimes I have 2 or 3 on the same day).</p>
  
  <p>Now this is the problem... On column C I need to SUM the hours of the last 7 days. And any given 7 days, not just last week. To do it manually is quite easy... the problem is that I need a formula as my records are quite large...</p>
  
  <p>Here with a small example (let's say that there was NO HOURS before 15/01/2009)...</p>
  
  <p>COLUMN A-------COLUMN B-------COLUMN C</p>
  
  <p>DATE--------------HOURS-------HOURS LAST 7 DAYS</p>
  
  <p>15/01/2009-------01:00-------01:00</p>
  
  <p>15/01/2009-------02:15-------03:15</p>
  
  <p>16/01/2009-------01:15-------04:30</p>
  
  <p>17/01/2009-------01:30-------06:00</p>
  
  <p>18/01/2009-------01:30-------07:30</p>
  
  <p>18/01/2009-------01:00-------08:30</p>
  
  <p>18/01/2009-------02:00-------10:30</p>
  
  <p>19/01/2009-------02:30-------13:00</p>
  
  <p>19/01/2009-------03:00-------16:00</p>
  
  <p>20/01/2009-------////////--------16:00</p>
  
  <p>21/01/2009-------01:00-------17:00</p>
  
  <p>22/01/2009-------01:30-------15:15</p>
  
  <p>23/01/2009-------02:00-------16:00</p>
  
  <p>I've been fighting for the last weeks trying to figure out a formula but no luck... any suggestions?</p>
  
  <p>Thanks</p>