S2k calculates fuel cost using WAC (Weighted Average Cost) also referred to as WAM (Weighted Average Margin). In the fuel inventory history you can see how this is calculated:



1-  The old weighted cost per gallon

2-  The new purchase cost per gallon

3-  The new purchase gallons (based on purchased # on fuel invoice normally based on NET in most states)

4-  The opening stick reading for that tank on day of delivery

5-  The new total gallons after deliver

6-  The new weighted cost per gallon


S2K takes the old cost (1) x gallons in ground at beginning of day of delivery (4) then gets the new cost (3) x new purchased gallons (3) and divides by the new TOTAL gallons after the delivery to get the new WAC (2)


($3.4194 x 12,057 = 41,227.7058) PLUS ($3.5336 x 8769 = 30986.1384) DIVIDED BY 20,826$3.4675