Mortgage Reduction over time

Vintagebrit

Hi, I have a tracker mortgage with The Coop and I'm in my 16th year of it out of 27.
My concern is that instead of the monthly reduction of balance going up, it is going down. I wondered whether it's because of the rate rises, but then as my payments are going up too, thought this couldn't be the case, especially as with no rate rise this last month, the reduction in my balance was one of the lowest yet.
I've written to the Coop and they've said all is fine. 
Why would this be happening? 

Strummer22

The capital paid off depends on the length of mortgage remaining and the interest rate. Higher rates mean less capital paid off early and more towards the end of the mortgage than would be the case on a lower rate. That way for a given mortgage term you arrive at zero balance at the same time for different interest rates. Put a few figures into a mortgage calculator to see how this works.

As for random month to month variations, I can’t help there 

MWT

Strummer22 said:

As for random month to month variations, I can’t help there 

The month to month variations usually reflect the variation in the exact number of days interest between payments changing slightly due to days in the month, weekends, bank holidays etc.