Hi Zenith
You seem to fundamentally misunderstand how to make a decision on a mortgage.
Let's say I have a mortgage of €100,000 with 20 years left. I have two years left fixed at 5%
I can fix today for 3% for two years.
The cost of the mortgage is the interest charged and not the repayment made.
The savings are very easy to estimate.
A reduction from 5% to 3% is 2% a year.
That is a savings of €2,000 per year in interest on a €100,000 mortgage
For two years, that is €4,000 interest.
(It's actually a bit less than that because you are repaying capital, but that will not be material.)
If the break-fee is less than €4,000, then it is worth breaking. In most cases, the break fee will be a lot less than the savings.
There is no need to look at the life of the mortgage.
All that is relevant is the remaining fixed rate period.
You might argue that your calculator is useful in working out the savings in repayments over the life of the mortgage by switching from a variable rate of 5% to a variable rate of 3%. But that is an irrelevant calculation in practice. If I know that AIB will be 2% cheaper than BoI for the remaining 20 years of my mortgage, it would be relevant. But I know that that will not be the case.
By the way, you are not alone in this. The Central Bank requires lenders to how the total cost of credit which is totally meaningless in a long-term loan where the rate is variable and the borrower can repay it early or switch to a cheaper lender or cheaper rate.
Brendan