Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
3,400
gallons
How to estimate it
Fermi’s official “Napkin math”
A car burns about a gallon every 30 miles. How heavy is a loaded 747? Maybe 400 tons, as much as 200 cars, all doing 550 mph.
- A car
- 1 gal per 30 mi
- 747 weighs like 200 cars
- ≈ 7 gal per mile
- 7 × 550 mph
- ≈ 3,850 gal
A car uses about 8 liters every 100 km. How heavy is a loaded 747? Maybe 400 tonnes, as much as 200 cars, all doing 900 km/h.
- A car
- 8 L per 100 km
- 747 weighs like 200 cars
- ≈ 16 L per km
- 16 × 900 km/h
- ≈ 14,400 L
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- 747-400 in cruise, Jeppesen flight plans (Aircraft Commerce)
- 3,350 to 3,400 gal/hr
- Cross-check: Hong Kong to Vancouver, 38,290 gal over 680 min
- ≈ 3,380 gal/hr
- Pilot rule of thumb, 10 to 11 tonnes an hour
- ≈ 3,300 to 3,600 gal/hr
- ≈
- 3,400 gallons (12,900 L)
Reference cited by Fermi: Aircraft Commerce 747-400 fuel burn performance analysis (Jeppesen flight plans): 3,350 to 3,400 US gallons an hour in cruise
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