>For example, if you make one extra payment per year, you will shorten a 30 year fixed rate mortgage by about 4.5 years.
This doesn't sound right. If I make 5 extra payments (either in 1 year or over 4 years), the mortgage will be shortened by 5 x 4.5 years = 22 years. I'm sure everyone would do this, 5 extra payments is super easy!
You misunderstood my original post. One extra payment per years means 13 mortgage payments, instead of 12. (Almost all US mortgages require monthly payments.) To be clear: This extra payment is strictly optional, but it used to demonstrate how curtailment can meaningfully reduce the life of your loan and the amount of interest paid.
This doesn't sound right. If I make 5 extra payments (either in 1 year or over 4 years), the mortgage will be shortened by 5 x 4.5 years = 22 years. I'm sure everyone would do this, 5 extra payments is super easy!