Tom Mockridge, the former Sky Italia boss who replaced Rebekah Brooks as chief executive of the newspaper publisher in July, told staff in an email that the Sunday tabloid sold 3.8m copies for its last edition.
The Guardian reports that the £2.8m charity donation was calculated after the 26p per copy charge from wholesalers and distributors was removed from the revenue.
It is understood that the money will go to the Forces Children's Trust, Barnardo's and Queen Elizabeth Hospital Birmingham, the three charities named in the paper's final edition on July 10.
The three organisations will get £933,000 each, and Mockridge revealed that five charities in Ireland will split the earnings from the Irish sales of the £1 paper.
News International opted to shut down the News of the World in July after the 168-year-old newspaper was dogged by a string of shocking allegations of phone hacking.
Mockridge also informed staff that 65 former staff on the paper have been redeployed in jobs within the newspaper publisher, including 30 who were retained on the Fabulous celebrity magazine now given as a supplement in The Sun on Saturday.
It is understood that 20 former News of the World employees have taken jobs at The Sun, while a further 11 have joined News International's mystery digital startup. Others have moved to The Sunday Times or the company's technology department.
A total of 81 employees left the News of the World after its closure, while around 20 were offered jobs within News International but turned them down. That leaves a further 100 that have been made redundant from the paper.
Speculation is growing that News International is preparing to take The Sun seven days a week to avoid missing out on the lucrative Sunday newspaper market.