How the monthly payment is calculated
An amortizing loan is repaid in equal monthly installments. Each payment covers that month’s interest first; the rest reduces the balance, so early payments are mostly interest and later ones mostly principal.
- M — monthly payment
- P — loan amount (principal)
- r — monthly rate = annual rate / 12
- n — number of payments = years × 12
Common values
| Loan amount | Monthly payment |
|---|---|
| 3,000,000 | 16,105 |
| 7,500,000 | 40,262 |
| 15,000,000 | 80,523 |
| 30,000,000 | 161,046 |
| 45,000,000 | 241,570 |
| 60,000,000 | 322,093 |
| 90,000,000 | 483,139 |
| 150,000,000 | 805,232 |
| 300,000,000 | 1,610,465 |
More detail
Why a longer term costs more
Stretching the same loan over more years lowers each monthly payment but raises the total interest — you’re borrowing the money for longer. Shortening the term or overpaying reduces total interest sharply, because it cuts the balance that interest is charged on.
Rate matters most
Interest is charged on the outstanding balance every month, so even a small change in the annual rate compounds into a large difference over 20–30 years. Always compare offers on the total-paid figure, not just the monthly payment.
Money tip. Before committing, check whether extra principal payments are penalty-free. Paying a little more each month early on — when the balance is largest — saves far more interest than the same amount paid near the end.
Frequently asked questions
Equal principal & interest vs. equal principal — what's the difference?
This calculator uses equal principal & interest (원리금균등): the same total payment every month, with the interest/principal split shifting over time. The alternative, equal principal (원금균등), keeps the principal portion fixed each month so the payment starts higher and steadily decreases — it pays less total interest for the same rate and term, but front-loads the cash outflow.
How much does raising the rate by 1 percentage point actually cost?
It compounds over every remaining month of the loan, so the effect grows with the term. Try the same amount and years above with the rate raised by 1 and compare the totalPaid figure — on a 30-year mortgage the difference is typically far larger than most people expect from "just 1%".
Does a shorter term always mean a smaller monthly payment?
No — the opposite. A shorter term raises the monthly payment (you're repaying the same principal faster) but lowers total interest, because the balance that interest accrues on shrinks sooner. Toggle the term above to see both move in opposite directions.