Hi,

I am interested in finding how the bank calculate the interest and principal I am paying each month.

I have statements every month which shows current interest rate, loan amount, principal, interest, outstanding.

I used to ask a friend a few years ago and the formula wasn't too complex and the result was exactly same as the statement. But I can't find it anywhere.

I tried to play in excel with ipmt function but that doesn't seem to be it.

Thank you

K

M = P i(1+i)^n / ((1+i)^n - 1)

Where:

M= payment amount

P= principal amount

i = interest rate

n = number of payments

Bankrate dot com website has great calculators and you can expand the amortization schedule and see all the details month by month. Good for checking things out. For example, I entered 100,000, 30 years, 5 % interest as an example. Excel formulas should work but one has to plow through the help to be sure you put the correct period in, i.e. 30 years really needs to go in as 360 for Months, etc.

Date Payment Principal Interest Total Interest Balance June 2015 $836.03 $217.28 $618.75 $618.75 $164,782.72 July 2015 $836.03 $218.10 $617.94 $1,236.69 $164,564.62

@hhgz

That is probably a good formula but isn't exactly what I'm looking for. Here is more details:

This month my statement shows (I modified the real values so formula wouldn't find these values)

Credit line: 1,000,000 THB

Current interest rate: 6%

Payment amount: 11,000 THB

Principal: 4,863 THB

Interest: 6,137 THB

Outstanding balance: 800,000 THB

Say I always pay 11,000 THB per month, how can I predict principal and interest breakdown for next month (assuming rate 6% is fixe)?

Thank you.

As mentioned earlier there are many calculators on the internet to provide your answer...many, many different types of calculators relating to mortgages, personal loans, credit card payments, extra payments, etc. Like gt10002000 mentioned Bankrate.com has a bunch of calculators covering almost any type of money repayment scenario.

@hhgz

That is probably a good formula but isn't exactly what I'm looking for. Here is more details:

This month my statement shows (I modified the real values so formula wouldn't find these values)

Credit line: 1,000,000 THB

Current interest rate: 6%

Payment amount: 11,000 THB

Principal: 4,863 THB

Interest: 6,137 THB

Outstanding balance: 800,000 THB

Say I always pay 11,000 THB per month, how can I predict principal and interest breakdown for next month (assuming rate 6% is fixe)?

Thank you.

I always found this useful:-

https://www.drcalculator.com/mortgage/