Commercial planes typically fly at cruising altitudes between about 30,000 and 42,000 feet (approximately 5.7 to 7.9 miles) above sea level. This range is optimal for fuel efficiency, safety, and passenger comfort. Flying at these altitudes allows planes to avoid most weather disturbances and turbulence, take advantage of favorable wind patterns like jet streams, and reduce air resistance, which lowers fuel consumption. The maximum service ceiling for many commercial aircraft is around 42,000 feet, beyond which the air becomes too thin for efficient engine operation and lift generation, and cabin pressurization becomes more challenging

. For example, common commercial aircraft cruise at these altitudes:

• Airbus A320: 33,000–37,000 feet
• Boeing 737: 35,000–37,000 feet
• Boeing 747: 33,000–37,000 feet
• Airbus A380: 35,000–43,000 feet

Some private jets can fly higher, up to around 47,000 feet, but commercial airliners generally stay below 43,000 feet due to design and operational limits

. In summary, commercial planes fly high-between 30,000 and 42,000 feet-to optimize performance, safety, and passenger comfort while minimizing fuel use and weather-related disruptions.