Loan amortization tables describe the contribution of a given payment to paying off a loan based on time. Loans can be written in a number of ways, with the focus on paying of a principal amount. This can be done by lowering the interest rate, or increasing the monthly payment.
While there are many calculators available online for inputs regarding interest rate and principal (solving for monthly payment), very few solve for all of the four input values. Solving for a term such as interest rate allows for a buyer to see if a loan is even possible in the current market.