If I put $ 3500 a year to the principal payment of my mortgage. How do I calculate the rest of the time in loan if I dump the allotted amount to the principal only? How many years would I knock off the total mortgage? I have about 24 years left at a little over 7% interest on $ 224,000.

You need an amortization calculator. This one seems good. It requires the original mortgage amount and original term but If you assume the mortgage is starting now, say it is 25 year mortgage for $ 224000, an extra $ 292/month ($ 3504/year) will save almost 8 years

The amortization calculator would work very good. Also if you got a printout when you closed _I did. You can simply look at the monthly principal payment. Go forward $ 3500 in principal and …there you are. So if there is about $ 100 in principal each monthly payment then you have moved forward almost three years.