Business loans are lending instruments designed to fund a number of things related to the operation, founding or expansion of an enterprise. Small business loans, commercial loans and bad credit business loans can be obtained from such sources as traditional banks, credit unions and specialized lending institutions. The total cost of business loans will depend on a number of things, including current lending interest rates. Business loan rates adjust up based on the creditworthiness of the enterprise. A business loan calculator can help company owners gain a rough idea of what costs might be, but the numbers are mere estimates.