I am aware that when paying off a repayment mortgage the proportion of monthly payments going towards the interest is higher towards the start and eventually the proportion lowers towards the end of the term of the mortgage.
For example, a £100,000 mortgage at 3% over 30 years would have a monthly payment of £421.60. During the first month, the interest paid is £250 and the capital paid is £171.60 meaning that my equity in the house would increase by £171.60 for that month. This is easy to calculate if I stick to the scheduled repayments of the mortgage and do not overpay.
However I want to calculate the equity in my home factoring in irregular overpayments.
As the interest on my online banking increases daily, I am checking my mortgage on my online banking the last day of each month and subtracting the amount of interest from the amount of paid to give me the equity I currently have. This works well but if I forget to check the interest on the last day then I will not be able to go back and see the interest at this point. Also I would not be able to calculate the future equity gained each month until reaching that month end.
So is there another way of doing this that would also let me calculate the future equity gained based on overpayments?