<prompt> Human: Hey PF!Ive been thinking about the 15-yr and 30-yr mortgage, as Im currently looking into buying a home in the near future. While Ive always had the idea of going for a 30-yr mortgage but budget for a 15-yr, my friends perspective has always just been to go for the 15-yr to save money. So I did a little calculation on total interest paid, for a 1 15-yr mortgage, 2 30-yr mortgage, 3 30-yr mortgage on a 15-yr mortgage payment, and 4 30-yr mortgage on a 15 year plan. Because I live in LA, CA, these are the parameters I assumed: 550,000 home 20 down, so 440,000 down payment 30-yr interest rate: 3.42 15-yr interest rate: 2.71Here is what I found for each of the four scenarios:1 monthly payment: 2977.57, total interest paid over 15 years: 95,9622 monthly payment: 1956.20, total interest paid over 30 years: 264,2323 if we paid 2955.57 monthly for a 30-yr mortgage, an extra 1021.37month, total interest paid over course of loan is 131,995, paid off in 16 yrs 1 month4 if we bumped the monthly payment to 3136.80 for a 30-yr mortgage, an extra 1021.37month, total interest paid over course of loan will be 122,644, paid off in 15 yrsSo roughly, in scenarios 3 and 4, we get the safety and flexibility of a 30-yr mortgage, pay both mortgages off in around 15-16 years, at a cost of an extra 27k-36k interest. Is it worth it for you guys? How do you guys put a value on flexibility? Or what influences you guys to make the decision between any of the 4 scenarios? Im not trying to say any option is better than the other, as I believe everyones situation is unique. Just wondering how each of you guys make up your minds and draw the line. If anyone is wondering, I used bankrates mortgage calculator to do the calculations.  <response>: Total interest paid is a very misleading way of looking at things because it ignores the time-value of money. Interest payments in year 20 are worth much less than interest paid today. The only way to compare the two scenarios is with a proper discounted cash flow analysis including what you would do with difference in payments. The benefits of a 15-year mortgage depend on the slope of the yield curve, or the spread between the two rates. This spread is historically high in recent years, indicating that the 15-year is a good choice relative to the 30-year. However, the low absolute level of the 30-year rate relative to todays dividend yields or AAA corporate bond yields indicate that a 30-year coupled with long-term investing of the payment difference could be the best choice. 