How much fuel is used for the different phases of the flight of a typical airliner?
From this site by Boeing for the B737-800: fuel used for TO and climb = 2,300 kg.
From this site: fuel burn in cruise for B737-800 is 2,500 kg/hr
From this site: fuel burn at idle of a CFM56 engine = 300 kg/hr, so for the half hour descent two engines burn through 300 kg.


Total fuel for a 4 hour cruise flight is therefore 2,300 + 4 * 2,500 + 300 = 12,600 kg. Percentages:


TO &amp; Climb =  19%
4-hour cruise = 79%
30-minute descent at idle: 2%