Not the monthly interest but the total on the whole Mortgage.

The easiest way would be to create an Amortization Schedule assuming no prepayments, and sum all the monthly interest payments. I don’t know of any formulas off hand that would do that for you.

Why do you need to know?

The suggestion above is the absolute hardest way to do it.

Calculate the monthly payment of the mortgage, multiply by the number of payments, and subtract the amount borrowed. Everything left is interest.

True that. Totally didn’t think of that, but its true. So for a standard 360 month mortgage multiply the P&I by 360 and subtract the original UPB.

you can do it with you TI Calc.

Put in the numbers and calculate the monthly payment.

E.g. say 200 K PV, 6% per year, 360 months

PV=-200000, I/Y=0.5, N=360 CPT PMT

PMT=1199.10

Now hit 2nd Amort

P1=1

P2=360

BAL=0.00

PRN=200,000

INT=231676.38

Reviving an old thread but besides the calculator method, does anyone has the full formula of calculating mortgage?

big excuse for not creating another topic but one question:

“An investor is looking at 150.000 home. If 20 % must be put down and the balance is financed at 9% over next 30 years, what is the monthly mortgage payment?”

why do I need to do this 150.000 (1-02) = -120.000 as 20% means like 150.000 - 20% = 30.000 and this sum of money goes to PV not 120.000 as it’s 80%

what did I missed?

You missed that the 30,000 is going to the seller of the home; it has nothing to do with the loan.

The loan amount is 120,000; that’s the PV on the loan.