From The Atlantic:
Having examined the finances of all 43 presidents (yes, 43; remember, Cleveland was president twice), we calculated the net worth figures for each in 2010 dollars. Because a number of presidents, particularly in the early 19th Century, made and lost huge fortunes in a matter of a few years, the number for each man is based on his net worth at its peak.HT: Economix
We have taken into account hard assets like land, estimated lifetime savings based on work history, inheritance, homes, and money paid for services, which include things as diverse as their salary as Collector of Customs at the Port of New York to membership on Fortune 500 boards. Royalties on books have also been taken into account, along with ownership of companies and yields from family estates.
The net worth of the presidents varies widely. George Washington was worth more than half a billion in today's dollars. Several presidents went bankrupt.
The fortunes of American presidents are tied to the economy in the eras in which they lived. For the first 75 years after Washington's election, presidents generally made money on land, crops, and commodity speculation. A president who owned hundreds or thousands of acres could lose most or all of his property after a few years of poor crop yields. Wealthy Americans occasionally lost all of their money through land speculation--leveraging the value of one piece of land to buy additional property. Since there was no reliable national banking system and almost no liquidity in the value of private companies, land was the asset likely to provide the greatest yield, if the property yielded enough to support the costs of operating the farm or plantation....MORE