On April 23, 1985, Coca-Cola threw out a formula it had sold for 99 years and replaced it with something sweeter, based on blind taste tests involving nearly 200,000 consumers, according to the company’s own account of New Coke’s launch.

Seventy-nine days later, on July 11, the original formula was back on shelves under a new name, Coca-Cola Classic, and New Coke was effectively finished. In between, the company that built its identity on being America’s drink triggered one of the angriest consumer revolts in corporate history, against a product the company’s own data said people actually preferred.

A Formula Nobody Asked to Change

Coca-Cola’s reformulation wasn’t a snap decision. Executives had watched market share erode against Pepsi for years, and internal taste tests, run on nearly 200,000 people, consistently favored the sweeter New Coke recipe over both the original Coke formula and Pepsi, according to the company’s history page on the infamous 1985 launch. On paper, the data supported the switch. What nobody had tested for was what would happen when the company took the original away entirely instead of simply adding the new formula alongside it on store shelves.

The Backlash Nobody Predicted

The consumer affairs hotline that normally fielded about 400 calls a day was getting 1,500 a day by June, and the company expanded its consumer affairs staff from roughly a dozen representatives to 180 within weeks just to keep pace, according to Coca-Cola’s own retrospective. Protest groups organized fast: the Society for the Preservation of the Real Thing formed within weeks of the announcement, and the Seattle-based Old Cola Drinkers of America claimed 100,000 members demanding the original formula’s return, per the company’s marketing blunder retrospective. Panic buying followed almost immediately, and one man in San Antonio reportedly spent $1,000 stockpiling old-formula Coke before local supplies ran dry.

Lynn Henkel, who managed Coca-Cola’s consumer affairs team through the crisis, later described what those calls sounded like: “People who called in were very upset; most just wanted to complain, but many shared personal stories about their connection to, and love of, Coca-Cola,” she said, according to the company’s own history.

Seventy-Nine Days

By July, the company had its answer. On July 11, 1985, Coca-Cola announced the return of the original formula as Coca-Cola Classic, sold alongside New Coke rather than replacing it, 79 days after the switch that had started the uproar. The reversal “led two network newscasts and made the front page of virtually every major newspaper,” according to Coca-Cola’s own history of the episode. Then-president Don Keough summed up the miscalculation at a company gathering afterward, admitting the company “didn’t pay attention to our consumers,” per the same retrospective. The episode is still cited across marketing courses today as one of the starkest examples of a brand underestimating the emotional weight customers place on a familiar product, a framing echoed in outlets including HISTORY’s account of the launch.

An Accidental Win

What looks like an unambiguous failure gets more complicated with distance. Coca-Cola’s overall sales grew after the Classic relaunch, and longtime CEO Roberto Goizueta later described New Coke less as a mistake and more as, in his words, an example of “taking intelligent risks” that reminded the public how much it loved the original, according to the company’s own history. Chief archivist Phil Mooney put it more plainly years afterward: “We became a better company because of this lesson,” he said, framing Coca-Cola’s role as custodian of something bigger than a beverage recipe, per the same source. New Coke itself limped on under later names before disappearing from shelves for good in 2002.

The Lesson That Outlasted the Formula

Coca-Cola had the data. Nearly 200,000 taste tests said the new formula won. What the spreadsheets missed was that people weren’t just buying a taste, they were buying a fixed point in their own history, and pulling it off the shelf felt like an erasure no focus group could measure. That gap, between what a test predicts and what a customer actually feels, is still the thing that trips up brands four decades later, only now it plays out over quarterly earnings calls and social media instead of a 79-day news cycle.