Look at chapter 5 in the Pilots Operating Handbook (Performance).
That's the official publication that you must use to meet the
requirments for pre-flight action. Try showing a Designated Pilot
Examiner or FAA check Airmen a spreadsheet programe on the day of your
checkride to compute your take-off and time fuel and distance to climb,
He'll give you the same answer as I.

The POH is valuable, the problem is knowbody wants to use it anymore.

Chad