Loan Interest Calculator
Calculate monthly payment and total interest for equal payment, equal principal, or bullet repayment.
Loan Details
e.g. $100,000 = 100000
Monthly Payment (Fixed)
₩506,685
* Actual loans may differ due to preferential rates, prepayment fees, and rounding.
Related life info & benefits
The loan interest calculator works out your monthly payment and total interest under both equal-payment and equal-principal repayment methods, so you can compare loan offers before committing. Enter the principal, annual interest rate, and repayment term to see your monthly payment and total interest at a glance.
Equal payment vs. equal principal — which is better?
With equal payment (principal + interest), you pay the same amount every month, which makes budgeting easy and keeps the early-stage burden lower. With equal principal, you repay the same principal each month while interest is charged only on the remaining balance — the early payments are larger, but total interest ends up lower. Equal principal suits borrowers with more cash on hand early on; equal payment suits those who prefer a predictable, level payment.
How the calculation works
Equal monthly payment = principal × monthly rate × (1 + monthly rate)^n ÷ ((1 + monthly rate)^n − 1), where monthly rate = annual rate ÷ 12 and n = number of repayment months. Total interest is (monthly payment × n − principal). The calculator applies this formula automatically to show your monthly payment and total interest.
Frequently Asked Questions
How much more interest will I pay if rates rise?
Even a 0.5 percentage point increase can add millions of won in total interest over a long repayment term under the same conditions. Try changing the rate to compare.
Does paying off early reduce my interest?
Interest accrues on the remaining principal, so early repayment reduces future interest — though some loans charge an early repayment fee.
How is a grace period different?
During a grace period you pay interest only, with no principal repayment, so the early burden is lighter — but the remaining term to repay principal shortens, raising later payments and total interest.
How is my loan limit decided?
It's set by regulatory ratios such as DSR (debt service ratio, which measures repayment capacity against income), collateral value, and the lender's own underwriting criteria.
Is a fixed or variable rate better?
Fixed rates tend to be better when rates are rising, and variable rates when they're falling. The longer the term, the greater the risk from rate swings.
How is a credit line (overdraft account) different from a regular loan?
A credit line lets you borrow only what you need up to a limit and pay interest only on what you've drawn, offering flexibility — but the rate is often higher than a standard loan.
* For reference only — actual loan terms and rates depend on the lender's underwriting.
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