Mortgage interest calculation formula

Narola1976

Sorry really thick as 2 planks and google has not been very helpful, so hoping someone can assist
I would like to know the formula for calculating the monthly interest amount and the minimum monthly payment on a mortgage. Here are my details

* Outstanding amount is £39307.64
* Interest rate is now 1.1% ( I am still on the old HSBC tracker rate, the one where they guaranteed never to be more than 1% above the base rate, which has worked well for us over the years)
* we overpay...minimum payment is £280, we pay £400

I know I could wait for the interest transaction to be reflected on the account as they have to change us to the new rate when the dust settles, but I would like to be able to calculate the interest, and also what the new minimum payment would be, were we not to overpay.

hope this all makes sense
thanks

Thrugelmir

How many months does your mortgage still have to run? 

Narola1976

Thrugelmir said:

How many months does your mortgage still have to run? 

It was a 30 year term originally, taken out in 2003 but stupidly as we didn’t know better and the rates were really very high back then and we were new to the UK we did interest only for the first 3 years...ouch. So technically due to be completed in 2033 but I know we have shaved quite a few months as we have been overpaying for a few years now. Thank you

Thrugelmir

With 13 years to run would be in the region of £270 per month.  

With a low capital balance owing. The impact of lower interest rates is actually quite small on your monthly repayments. As majority of your repayment is capital not interest.