Flu, I think you’re missing one variable in your calculation. The ~$1000 you’re saving each month. That $1000 will be 180k after 15 years. If you can average 1.5%return on that 180k, it’ll be 215k in 15 years. That’s enough to pay your mortgage for the following 10 years. If you don’t take all of it out at 15 years, it might stretch to 11 years. If you can average 3%, that 180k will grow to 280k. That’s enough to pay your mortgage the the next 13 years. Might be able to stretch to 14 years if you don’t take it all out in 15 years. So it seems like you can still retire in 15 years with a 30 years mortgage.