"From what we've seen from iTunes, it's gone bonkers," he told BBC Radio 4's Today program on Monday. "Within four or five minutes we had a million quid ($1.7 million)."
The single, which premiered on the British version of the TV talent show X Factor Sunday night, went on sale online Monday morning with proceeds going to help fight the spread of the hemorrhagic virus in West Africa.
"iTunes haven't been able to refresh their charts because the demand has been so vast," said the veteran rocker.
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Some of the biggest names in the British music industry gathered at a London studio on Saturday to record the song, including boy band One Direction, U2's Bono, Robert Plant and Coldplay lead singer Chris Martin.
The lyrics have been updated from the 1984 original Do They Know It's Christmas. That version, featuring artists like Bono, George Michael and David Bowie, went on to sell 3.7 million copies and raised $14 million for famine relief.
Aided by online digital sales, it seems likely that the 2014 version will smash previous Band Aid single sales.
"That isn't what [Band Aid co-founder] Midge [Ure] and I expected when we knocked off an OK song 30 years ago," explained Geldof.
"But, every time it's worked. Without question, without any shadow of a doubt, there are hundreds of thousands, if not millions alive today who would have died of hunger."
Geldof relaunched the Band Aid cause last week, after he said the United Nations contacted him, saying help was urgently needed to prevent the disease from spreading beyond West Africa.
Ebola has killed more than 5,000 people since it broke out in West Africa earlier this year according to the World Health Organization, mostly in Sierra Leone, Liberia and Guinea.
Band Aid 30 lyrics
It's Christmas time, and there's no need to be afraid
At Christmas time, we let in light and banish shade
And in our world of plenty, we can spread a smile of joy
Throw your arms around the world
At Christmas time
But say a prayer, pray for the other ones
At Christmas time, it's hard but while you're having fun
There's a world outside your window, and it's a world of dread and fear
Where a kiss of love can kill you, and there's death in every tear
And the Christmas bells that ring there are the clanging chimes of doom
Well tonight we're reaching out and touching you
No peace and joy this Christmas in West Africa
The only hope they'll have is being alive
Where to comfort is to fear
Where to touch is to be scared
How can they know it's Christmas time at all
Here's to you
Raise a glass to everyone
And here's to them
And all their years to come
Let them know it's Christmas time after all
Feed the world, let them know it's Christmas time again
Feel the world, let them know it's Christmas time again
Heal the world, let them know it's Christmas time again