Government cuts will claim 28,000 police jobs, the Association of Chief Police Officers (Acpo) has said.
The Acpo estimate for England and Wales has been made in a confidential memo to ministers published in the Guardian.
Acpo predicts the jobs of 12,000 police officers and 16,000 civilian staff will be lost as a result of spending cuts.
Meanwhile, the Winsor review of police pay and conditions to be unveiled on Tuesday is expected to recommend cutting £180m in annual bonuses.
Greater Manchester Chief Constable Peter Fahy confirmed the job loss forecast - representing a reduction of about 12% of posts - to the Guardian.
He said: "We will have fewer staff, the same or more demands, and will need to incentivise staff to produce higher quality."
Pay structure
The government is planning to cut its funding for the police by 20% by 2014-15.
The 43 forces in England and Wales currently employ about 244,000 people, comprising 143,000 police officers and 101,000 civilians.
The review of police pay by former rail regulator Tom Winsor is set to suggest scrapping a series of allowances and bonus payments, and reducing the amount of overtime.
It is also expected to consider areas such as police housing, travel allowances and shift patterns, in an attempt to modernise working practices and make the service more cost-effective.
Acpo said overtime was needed to allow forces "to respond flexibly to any event or crime at any time whether it be a flood, a major murder investigation or public order incident".
BBC home affairs correspondent Danny Shaw says the Acpo figures are the latest and most reliable figures on police job cuts since Chancellor George Osborne's Spending Review last October.
Paul McKeever, chairman of the Police Federation of England and Wales, said the proposed cuts come after a two-year pay freeze for officers.
He told the BBC Radio 4 Today programme: "For many officers it is going to mean them losing their homes or not being able to put the heating on.
"That is the reality for people out there and they are very angry and upset about a government that is out of touch and doesn't understand policing."
Mr McKeever said there was "spin and negative stories coming from Home Office advisers" who used "isolated examples" to suggest officers were regularly claiming excessive and unjustified overtime.
Home Secretary Theresa May has warned that reductions in police pay are "unavoidable" in order to minimise front-line job losses.
Speaking at the weekend, she said: "We are working with police forces to identify savings that actually go beyond the reduction on the central policing grant in the next four years.
"I know that some will reject in principle the very idea of reviewing pay and conditions, but I remind them that those savings will save the jobs of thousands of police men and women.
"Nobody is pretending decisions like these will be easy."
'Blind arrogance'
Shadow home secretary Yvette Cooper said the figures were the "latest nail in the coffin for the prime minister's claim that he would protect the front line at all costs".
"Chief constables are being put in an impossible position by a government that seems happy to ride roughshod over public safety and the morale of the police force," she said.
"The government is cutting too far and too fast with 20% frontloaded cuts.
"The home secretary and her ministers have a blind arrogance in their dealings with the police.
"Rather than working with them, they are bludgeoning police numbers, their budgets and their operational capacity."
Blair Gibbs, from the right-leaning think tank Policy Exchange, said the review was "long overdue" as current working arrangements were "outdated".
"We need pay and conditions that reflect the white collar workforce... that we want policing in the 21st Century to be with many more graduates, many more women, more civilian trained staff supporting the police, and that means, ultimately, modern working conditions."
The former deputy assistant commissioner of the Metropolitan Police, Brian Paddick, suggested forces should save money by changing rules on overtime to bring them in line with the private sector.
He told the BBC: "Policing is a very unpredictable business, you never know when you're going to have a major incident for example. But the regulations about overtime are antiquated."
Source: http://www.bbc.co.uk/news/uk-12672329