Although I’d already sorted out my mortgage with HSBC, I was curious to know how interest rate rises and lump sum payments would affect my monthly mortgage costs. I did a little looking around and found a few online calculators but by far the best thing I discovered was an excel spreadsheet available here. With it you can see how much interest you are paying every month, how much you have left to pay off the mortgage, what happens if interest rates rise and what happens if you make one off payments. All very useful.
I added an extra couple of columns – one for a running total of how much interest I’d paid and a second to show how much I’d have in the way of savings assuming I saved X amount per month. This second column let me see at what point my savings = the remaining loan amount and so estimate when I could realistically pay off the mortgage in full.