Harold Camping speaks during a taping of his show Open Forum in Oakland, Calif. Camping, the Northern California preacher whose radio ministry spent millions of dollars last year predicting a fiery apocalypse that failed to materialize has apologized to his followers in an open letter, saying “we humbly acknowledge we were wrong” and “we have no new evidence pointing to another date for the end of the world.” (Marcio Jose Sanchez/AP)

Harold Camping, a Christian radio evangelist whose brimstone-ridden sermons stoked an international media frenzy in 2011 after his Armageddon prophecies coursed through the Internet and social media, died Dec. 15 at his home in Alameda, Calif. He was 92.

The death was confirmed by Family Radio, his Oakland, Calif.-based broadcasting company. He suffered a stroke in 2011.

That life on Earth continued after May 21, 2011, was a crushing disappointment to Mr. Camping, his legion of devout followers and millions who listened to his Family Radio network.

A civil engineer by training, Mr. Camping was a self-taught and self-described Bible scholar who developed his end-of-world prophecies through complex mathematical calculations and, he said, “clues sprinkled throughout the Bible.”

“It is going to happen,” he told NPR in early May 2011. “There is no Plan B.”

He reportedly spent tens of millions of dollars to spread his doomsday message. His May 21 prediction was plastered on more than 5,000 billboards across the country. He had 100 million pamphlets printed in 61 languages, including some that read, “The End of the World is Almost Here!”

His volunteers canvassed the country, including dozens who walked Washington’s Mall handing out fliers that reminded passersby to “Save the Date.”

Through the Internet and social-media platforms, Mr. Camping’s bold prognostication “was made all the more accessible to a wider demographic and more quickly,” said Jay Johnson, a religion professor at the Graduate Theological Union in Berkeley, Calif. “He benefited from it in a way that no other [doomsday predictors] previously had.”

In his deep, gravelly voice, Mr. Camping told listeners that Judgment Day would begin with a tremendous earthquake. True Christians, he said, would experience the rapture. In all, he predicted, 200 million saved souls would ascend to heaven.

Many of Mr. Camping’s followers sold their homes, quit their jobs and depleted their savings accounts to help finance his end-of-the-world campaign.

After May 21 came and went, Mr. Camping emerged from his California home “flabbergasted.” He called May 21 an “invisible Judgment Day” and said his calculations had been off by six months. The real Armageddon, he said, would come on Oct. 21, 2011.

Did his incorrect May prediction affect his reputation among followers? A moot point, he said.

On “October 21 of this year, the whole world is going to be annihilated, and never be remembered. So what legacy am I going to leave to anybody?” Mr. Camping told the online religion magazine Killing the Buddha in 2011. “The only thing is that I hope that there are people who are listening that will begin to plead with God and begin to cry out.”

When the October prediction did not come true, Mr. Camping retired from his radio work.

Harold Egbert Camping was born July 19, 1921, in Boulder, Colo., and was raised in the Christian Reformed Church, a Protestant denomination. In the 1980s, Mr. Camping split from the church to form his own congregation.

Survivors include his wife of 71 years, Shirley Vander Schuur. A complete list of survivors could not be confirmed.

Mr. Camping was a 1942 civil engineering graduate of the University of California at Berkeley and worked as an engineer for a government contractor during World War II. He started a construction business after the war but sold the firm to pursue a religious calling, he said.

He began preaching his blend of the Christian gospel over the airwaves in the late 1950s. He opened his first station in the San Francisco area, he said, because there was no Christian radio competition.

As his popularity grew and donations flowed in, Mr. Camping bought more radio stations in California and expanded his operation’s reach.

By the end of his life, Mr. Camping’s Family Radio — its slogan was “Feeding God’s Sheep” — had become a $100 million media empire. His worldwide network was broadcast over scores of affiliated radio stations as far away as Taiwan and Ghana.

He ventured into end-of-days prediction in the early 1990s. He wrote two books — “1994?,” published in 1992, and “Are You Ready?,” published in 1993 — explaining his calculations and offering guidelines for preparing the faithful for the rapture that he said would arrive Sept. 6, 1994.

Mr. Camping was not the first American evangelist to claim to know mankind’s expiration date.

“One thing that sets [Mr. Camping] apart from the broader kind of apocalyptic flavor of Christian history is his insistence on an actual time and date. That’s quite remarkable because it’s easily disconfirmed,” said Johnson, an expert on doomsday religious groups. “To have that firm confidence to have the ability to predict such an astonishing thing with such prescience was really quite stunning.”

When his first prophecy in 1994 did not come to fruition, Mr. Camping said his revised calculations pointed to another year: 2011.

After the Oct. 21, 2011, Judgment Day passed, Mr. Camping apologized on the airwaves for misleading his listeners. He said he regretted his pronouncements and said he would retire.

“Let’s pray more than ever for God’s mercy,” Mr. Camping said in a message. “God is in charge, and we must always keep that in mind.”