Is there an equation for calculating this?

Thank you so much!

Yes, but the formula is just a guideline... and it takes the person's weight into account.

Calorie Calculator for Runners: Runner's World (http://www.runnersworld.com/cda/caloriecalculator/0,7153,s6-242-306-313-0,00.html)

So 123lbs for Patrick, 26.2 miles for the run: He burned about (give or take) 2500 calories.