Treasury Secretary John Whitehead said the $2 billion figure previously used in relation to the cost of the earthquake referred to Earthquake Commission liabilities only.
Treasury's "ballpark" estimate of the total cost to householders, insurance companies, businesses and the Government was double that.
"The cost faced by the EQC, individuals, and insurance costs will probably be of the order of $4 billion," Mr White head said.
In terms of the economic impact it was early days "but the pattern of these is certainly a short term drop in activity of businesses being unable to function and ...there's always a risk of businesses failing.
"In the slightly longer term when you've got that reconstruction effort, a big amount of that going on tends to raise GDP (gross domestic product)."
But Mr Whitehead stressed that there were a "very wide range of estimates" on costs at the moment because officials were still to "get down to what's actually happened on the ground".