FCOM PRO.NOR.SRP.01.50 :
Cost Index for Long-Range Cruise
The flight crew can use the table below to find an approximate Cost Index value that is calculated for cruise at long-range cruise speed. This value is valid for CRZ FL = OPT ALT ± 10000ft.
AIRCRAFT..........................ENGINE..........................CILRC
............................................................ ......kg/min.........100lb/h
....................................CFM 56-5-B4..........25kg/min........35lb/h
A318/A319/A320/A321....CFM 56-5-B6/B7.....30kg/min........40lb/h
....................................CFM 56-5-B8/B9.....15kg/min........20lb/h