The estimate released Wednesday by the U.S. Fish and Wildlife Service comes a year after the agency designated 1.8 million acres in 28 counties as habitat critical to the frog's survival.
The cost to developers of regulatory delays and of buying land elsewhere to offset projects they are building on frog habitat were among the factors federal officials considered.
Al Donner, a spokesman for the federal agency, says developers could save money if they start the regulatory process early.
The frog, the largest species native to the Western U.S., was listed as threatened in 1996.