Savings Interest Calculator
Enter a deposit or monthly saving amount, annual rate and term to see interest before and after tax and the amount at maturity. Switch between simple and monthly compound interest to compare products.
Korean tax basis: 14% interest withholding (Income Tax Act Art. 129) + 10% local income tax (Local Tax Act Art. 103-13) = 15.4%. Source: law.go.kr, checked 6 Oct 2026. Monthly estimate.
How to use the interest calculator
- Choose a lump-sum deposit or a monthly savings plan.
- Enter the amount, annual rate and term, and pick simple or monthly compound interest.
- Interest after tax and the maturity amount appear instantly.
Comparing savings rates
- A 6% monthly plan earns about what a 3% deposit does, because each installment is invested for only part of the term.
- Check bonus-rate conditions — headline rates often require salary transfers or card spending.
- Deposit insurance in Korea covers ₩50 million per bank (principal plus interest).
FAQ
How is deposit interest calculated?
Simple interest = principal × annual rate × months ÷ 12. ₩10,000,000 at 3% for 12 months earns ₩300,000 before tax.
Why does a monthly savings plan earn less than I expect?
Each deposit earns interest only from the month it’s paid in, so on average your money is in the account for about half the term.
What tax applies to interest in Korea?
15.4%: 14% income tax withholding (Income Tax Act Art. 129) plus 1.4% local income tax. Choose a different rate for other countries.
How big is the difference between simple and compound?
Small over short terms — about ₩4,000 on ₩10,000,000 at 3% for a year — and larger over longer terms.
Why does my bank show a different number?
Banks count actual days, apply bonus rates and round tax differently. This is a monthly estimate.