The proposed cost of a new, acute care hospital in Prince George’s County is slightly less than earlier estimates, new documents show.

Dimensions Healthcare System’s application to Maryland regulators says that the new hospital, planned for Largo, would cost about $630 million, rather than the $645 million officials had previously projected. Of that amount, about $416 million, divided evenly, will come from the public funds from the state and from Prince George’s County. The rest will come from bonds, loans and other lines of credit, documents show.

The number of in-patient beds is down too, from about 259 to 231. However, plans show that the number of proposed “observation” beds, which are used to assess a patient’s needs, is now up to 68, more than double original estimates.

Officials said that the changes stem from a detailed refining of earlier plans, which began to be drawn up in 2011. Maryland health officials must approve the plans before construction can begin.

The documents, filed this month, show for the first time the costs associated with actually doing the deal. About $100 million will be needed in working capital for startup costs, which will come primarily from bond sales, documents show.

State health-care officials will begin their formal review soon. Plans call for the new hospital, which is to replace 265-bed Prince George’s Hospital Center in Cheverly, to become part of the University of Maryland Medical System. The hospital is supposed to open in late 2017, but the filing, put together by the University of Maryland Medical System and Dimensions, suggests that timeline could slip slightly to sometime in 2018.

The hospital is supposed to have several high-end medical specialities, aimed at luring back patients with medical insurance who in many instances have left the county to obtain medical care. In recent years, Prince George’s Hospital Center had become the hospital of choice for low-income residents, and many of the county’s more than 80,000 uninsured residents, who often used expensive emergency services because they did not have a primary care physician.