how to estimate table size?

Hi everybody,

i want to estimate the table sizes for each of my tables before inserting 1 million records in each of them. I also want to estimate the corresponding size of the indices. could any one of you pls guide me on how to go about it? Pls take the example of Employee table and mention the steps. At present I am taking the help of TOAD to estimate the table sizes. I want to know how can we do it without taking help from any of the tools.

The motive behind doing all this is to foretell the clients about the expected size of database after they have fed in i million records in each of the tables.

thanks a lot

Parijat Paul