It depends vastly.. VASTLY on where you are. Salaries in urban New York, San Francisco are vastly different from salaries in Iowa say.. simply due to the cost of living difference.
Salaries are also very different between different fields.
One misconception I see here, I would like to clear. A PhD is a working education… a postdoctoral position is a job (NOT an educational thing..)
How much you save depends on you… Do you smoke? Will you want to have coffee at Starbucks everyday? Are you willing to eat one meal a day?
Most PhD students in sciences that I know of, survived on their stipends and had a reasonable quality of life (not unlike existing stipends in India).
Sourabh Dube, Assoc. Professor of Physics at IISER, Pun
Source: Quora Digest