Crack Spread Basics

"Crack Spread" is the difference between the prices of the oil products and oil itself.
The simple 1:1crack spread per barrel is  given by formula 42*RB - CL. For example, today Peppa George II bought 1:1 Jan16-Jan16 spread for (42 *$1.3512 -$48.96)/barrel and sold for (42*$1.3579-$48.8)/barrel. Those numbers are 7.7904 and  8.2318, respectively.  Both RB and CL contracts are for 1000barrels.  $Profit is (8.2318-7.7904)*1000 -14.88 which is about $425.

For more information google Crack Spread Handbook at cme.com