How to find the remaining balance on a loan

AMORT splits a run of payments into interest and principal and updates the balance as it goes, so the payoff amount is always one recall away.

Problem

Four years into a $200,000, 15-year mortgage at 5.5%, how much interest and principal have you paid, and what do you still owe?

Keystrokes

fFINx≷y
0.00
Start clean.
15g12×n
180.00
180 monthly payments.
5.5g12÷i
0.46
Monthly rate.
200000PV
200,000.00
The amount borrowed.
PMT
−1,634.17
The monthly payment.
0n
0.00
Resets the payment counter, since AMORT counts payments in n.
48fAMORTn
−40,015.81
Amortizes the first 48 payments and shows the interest in them.
x≷y
−38,424.35
The principal repaid in those payments.
RCLPV
161,575.65
The balance still owed.

Answer

In the first four years you pay $40,015.81 of interest and $38,424.35 of principal, and you still owe $161,575.65.

Why it works

fAMORTn takes the number in the display as a count of payments. It works out the interest and principal in each one and leaves the totals in X and Y. It also lowers PV to the new balance and adds the payments to n, so the next fAMORTn carries on where this one stopped.

Things to know

AMORT rounds each payment’s interest to the number of decimals shown, just as a lender rounds to the cent. Leave the display at two decimals for amounts in dollars.

Because AMORT changes PV and n, key the loan again before starting over from the first payment.

Questions

How many payments have I made so far?

RCL n shows the running count.