Those jets are valued at about $4.5 trillion, Boeing said. The jet maker increased the predicted need in its annual 20-year forecast, released Tuesday, by 1.5 percent -- from a 33,500-jet estimate last year, when the planemaker raised its two-decade forecast by 8.4 percent.
"The world's aviation market is broader, deeper and more diverse than we've ever seen it," said Randy Tinseth, vice president of marketing for Boeing Commercial Airplanes. "It has proven to be resilient even during some very challenging years and is driving production rate increases across the board."
Boeing estimates airlines in the Asia-Pacific region will lead the demand for new jets. Europe and North America will come in second and third in demand. Boeing will have to compete with Airbus and other competitors, including Bombardier, Embraer, and China's state-owned COMAC, for those sales.
The world's airlines fly almost 20,000 planes today. That number is expected to rise to almost 40,000 by 2031, Boeing said.
Boeing and Airbus are both speeding up production to meet a growing order backlog. Airbus, based in France, announced on Monday that it will begin assembling A320s in Alabama, with deliveries to begin in 2016. Boeing, meanwhile, is speeding up production of the competing 737 in Renton.
Chicago-based Boeing reduced its projection for the number of freighter airplanes that will be sold. It says the cargo market remains sluggish.
Sales of widebody jets, like Boeing's 787, 777 and 747, all made in Everett, will account for almost $2.5 trillion in deliveries. However, orders will slow for the largest such planes, the Boeing 747 and Airbus A380 superjumbo, Boeing said.
Fuel bills for four-engine planes such as the 747 and double-decker A380 have been pushing airlines toward longer-range, more-fuel-efficient twin-engine models. Orders last year for Boeing's 777 reached a record 202, while the new 747-8 had only seven sales, according to Boeing's website.
There also will be fewer sales of narrow-body planes, Boeing said. That category, which includes the 737 and the Airbus A320, makes up the bulk of the global fleet.
Passenger traffic will rise about 5 percent a year in the next two decades, Boeing said, while cargo traffic will increase 5.2 percent annually, down from a previous forecast of 5.6 percent.
Boeing has issued annual 20-year forecasts since 1964. Airbus, too, issues an annual forecast, the latest of which is not yet public. Both companies will do public-relations battle at the Farnborough International Airshow next week in England.
Shares of Boeing on the New York Stock Exchange closed up Tuesday 1.49 percent, at $74.27.