jai6638, as False Capture has indicated, all Transport category aircraft must meet APPROXIMATELY (Exactly if obstacle limited) the same performance with one engine inoperative. That is, the 2 engined aircraft meets it's requirements on 1 engine, the 3 engined aircraft meets it's requirements on 2 engines, and the 4 engined aircraft meets it's requirements on 3 engines. (OK purists, in non-obstacle limiting circumstances the 3 and 4 engined aircraft do slightly better).
Now, in normal operations where an engine doesn't fail, all of the aircraft are "given back" the engine that was assumed failed. The 2 engined aircraft now has 2 instead of 1 (100% increase), the 3 engined aircraft now has 3 instead of 2 (50% increase), and the 4 engined aircraft now has 4 instead of 3 (33.3% increase). The 2 engined aircraft in NORMAL operations now has 3 times the thrust excess than does the 4 engined aircraft. Apart from the economics, safety in circumstances such as wind-shear recovery is dramatically increased.
Bolty McBolt, a fair question to compare the B777-300 to the B747, but it still falls a little short. Perhaps a better comparison would be between the B777-300ER and the B747, now we're talking approximately equal commercial uplift / distance capability.
I'm doing a 7 hour sector on a regular B777-300 tonight, I'll try to convince the dispatcher to give me a comparative fuel figure for the B747-400.
Regards,
Old Smokey