LOS ANGELES — The 2028 Olympic and Paralympic Games could generate between $20 billion and $40 billion in economic activity across five Southern California counties, according to a new study commissioned by the LA28 Organizing Committee. The analysis by the Los Angeles County Economic Development Corp. covers spending during the years leading up to the Games as well as the roughly four weeks of Olympic and Paralympic competition. It estimates the Games will produce about $15 billion to $24 billion in regional value after accounting for the goods, services and energy required to support them. The five-county region includes Los Angeles, Orange, Riverside, San Bernardino and Ventura counties. The new projection is higher than a 2025 estimate from the Southern California Association of Governments, which put the Games’ regional value at $13 billion to $17 billion. The forecast arrives as Los Angeles prepares to host the Summer Olympics for the first time since 1984, while cities that hosted more recent Games have faced major cost overruns. Brazil and Russia, among other hosts, spent tens of billions of dollars more than initially projected on stadiums, transportation and other infrastructure. Some of those facilities later saw limited use. LA28 says it plans to limit those risks by relying largely on existing stadiums and hotels and by using private financing. The 1984 Los Angeles Games, organized under a similar model, ended with a reported $215 million surplus and are widely viewed as one of the few financially successful modern Olympics. The organizing committee has set an operating budget of $7.15 billion. It says that budget will be covered by sponsorships, ticket sales, merchandise and an International Olympic Committee contribution of nearly $1 billion. But a profitable organizing committee would not necessarily mean the region receives the full economic benefit projected in the study. The 2024 Paris Olympics turned a profit, yet a French government audit found that overall economic activity fell well short of a pre-Games estimate of a $12.8 billion windfall. Andrew Zimbalist, professor emeritus of economics at Smith College, said the new assumptions appear more realistic than those used in some earlier Olympic forecasts but questioned the study’s input-output methodology. The Games’ ultimate effect, he said, will depend in part on whether Olympic visitors outnumber people who avoid Los Angeles because of congestion, higher prices or other disruptions. Los Angeles typically attracts roughly 12 million to 15 million tourists each summer, creating a large pool of visitors who could alter their plans during the Games. “If the number of people who come because of the Olympics is greater than the number of people who stay away because of the Olympics, then there could be a positive net impact,” Zimbalist said. The study attributes its largest projected share of economic activity — about $8.35 billion — to transportation, airport and venue projects being built by city and county governments rather than to direct LA28 spending. Those projects include expansions of the LA Metro system and a transit connection to Los Angeles International Airport. The report also projects about $2.8 billion in public funding for transportation and federally supported security costs. While LA28 says its operating budget will be privately financed, taxpayers will still help pay for infrastructure and public safety tied to the event. About 2 million visitors are expected to come to the region, according to the study. Their spending in Los Angeles County on lodging, food and other goods and services is estimated at between $1.6 billion and $4.3 billion. A separate workforce analysis connected roughly 124,000 jobs to Games-related activity, including positions for shuttle and bus drivers, carpenters, security guards and construction workers. The projections will likely remain subject to revision as projects advance, contracts are finalized and the region’s transportation, housing and tourism markets respond to the Games. The central question for residents will be whether the promised benefits translate into lasting improvements and broadly shared economic gains — rather than temporary spending concentrated around Olympic venues.