UPDATE SATURDAY 7 PM: Almost 23 million viewers in the U.S. watched the coverage of the Royal Wedding of Prince William and Kate Middleton from 6AM to 7:15AM ET on Friday across 11 networks. That outpaces the estimated 17 million who tuned in for Prince Charles and Diana’s wedding in 1981, which was carried by the Big 3 broadcast networks in the era before the proliferation of cable. According to Nielsen, the combined viewership for yesterday’s nuptials was 22.77 million on ABC, CBS, NBC, Telemundo, Univision, BBC America, CNN, E!, FOX News, MSNBC and TLC. In households, the William-Kate wedding drew 18.6 million vs. 14.2 million for Charles-Diana. As for Charles’ wedding to Camila Parker Bowles in 2005, it was watched by 3.65 million viewers.

SATURDAY AM – Deadline’s London Editor Tim Adler reports: Nearly 27 million British TV viewers watched the Royal Wedding live, according to the three main broadcasters of Friday’s event. That is still fewer than the 28.4 million who watched the 1981 wedding of Charles and Diana on BBC and ITV. The BBC peaked at 20 million viewers when Prince William and Kate Middleton exchanged vows; ITV peaked at 6 million; and Sky News at 661,000. Those watching on other channels –-  Channel 4 and Five –- made up only 1% of the Brit TV audience. The figures still put yesterday’s Royal Wedding among the top 10 of programs ever watched in the UK, although the 1966 World Cup final and Princess Diana’s 1997 funeral drew bigger audiences.

Brit officials estimated the Royal Wedding would be watched by 2 billion people worldwide. That left ratings experts over here scratching their heads. The biggest-ever global audience for a single TV event was an estimated 1 billion in 2008 for the opening ceremony of the Olympic Games in Beijing, says the BBC. Countries including Indonesia, Bangladesh and Nigeria do not even have TV ratings. “It’s absurd to think that one-third of the world’s population watched the Royal Wedding,” one analyst said. “Most people around the world were asleep. If you think about it for a moment, it’s nonsense.”

BBC: The BBC has predictably claimed UK ratings victory for the Royal Wedding. Seventy percent of UK TV viewers watched the BBC’s coverage at the peak moment when Prince William and Kate Middleton exchanged vows. Twenty million UK viewers watched live on BBC TV and via its online iPlayer service. Across the day, 34.7 million viewers watched the Beeb’s coverage. The BBC website crashed due to the volume of computers trying to access it. BBC News website got 9.4 million uniques — 4 million in the UK and 5.4 million internationally. BBC America also carried BBC1’s coverage live, which was also streamed around the world through the various international BBC channels. Another 40 broadcasters in 25 countries including the U.S. also carried the BBC Royal Wedding live feed.

ITV: ITV, meanwhile, won a peak audience of 6 million. This is seen as a victory for ITV: Not only have UK critics said its Royal Wedding coverage was livelier, but a 3-to-1 ratio in favor of the BBC is a good result for the UK’s biggest commercial terrestrial; media commentators had expected something more like 5-to-1 in favor for the Beeb. Peter Fincham, ITV director of television, said: “We are very pleased that the audience increasingly chose to stay with us during the afternoon, which also reflects the fantastic feedback we have had about our coverage.”

Sky: Sky News got a UK peak viewing figure of 661,000 at 11 AM London GMT (3 AM PST) –- nearly triple its average peak time audience –- as people tuned in to see that dress. The Sky News website got 1 million uniques, roughly double what it gets in a normal day. And the Sky News iPad app had its best performance day since launch six weeks ago at 35,000.