The company issued the estimate Thursday, the first time it has put a total cost on the catastrophe.
BP said it expects to spend a total of $44 billion after tax deductions are factored in. The new estimate included $5.2 billion in new pre-tax costs.
In 2010, one of the company's deep-sea wells blew out off the coast of Louisiana, leading to the sinking of the Deepwater Horizon drilling rig. Eleven rig workers were killed in the explosions and millions of gallons of oil spewed into the Gulf for 87 days.
BP said the cost estimate included all "remaining material liabilities."
The company has settled the majority of the claims filed against it by companies, local, state and federal governments and individuals, such as scores of fishermen.
It said its new pre-tax $5.2 billion cost estimate covers "all outstanding business and economic loss claims" stemming from litigation filed by individuals and companies.
In April, a federal judge approved a $20 billion settlement over economic and environmental damage between BP and state and federal governments, one of the largest corporate penalties in U.S. history.
"Importantly, we have a clear plan for managing these costs and it provides our investors with certainty going forward," Brian Gilvary, BP's chief financial officer, said in a news release.
The cost estimate was not far from what was expected, analysts said.
"It's important to put a figure on it and move on," said Eric Smith with the Energy Institute at Tulane University in New Orleans. "They are trying to put a cap on it and reassure that there is an end to this and that they are now confident enough to say what the end is."