Mortgage overpayment calculator

alystotty

Hi, we are come into a chunk of money and want to pay off our mortgage. However, we are just about to enter the 2nd year of a 5 year fixed rate mortgage (1.57%) so I'm trying to work out if we would save more in interest by paying it off in one lump and taking a 5% ERC hit or whether to pay a lump sum of 10% (free of ERC) each year for 4 years and then pay off the balance. The lovely overpayment calculator can't help as I can't put in pay off x amount for 4 years then 1 lump some to pay it off. Anyone clever enough to work it out for me?