Savings Interest Calculator

A lump-sum deposit puts the whole amount in at once and pays principal and interest at maturity. A monthly savings plan pays in the same amount every month, so each payment earns interest for a different number of months: the first earns the most and the last only one month.

Principal × annual rate × (months ÷ 12) gives 350,000 KRW before tax. Withholding tax of 15.4% (53,900) leaves 296,100 KRW after tax and a maturity payout of 10,296,100 KRW.

The formula is monthly deposit × (annual rate ÷ 12) × n(n+1) ÷ 2, and with n = 12 that is 78 months of interest. Total deposits of 3,600,000 KRW earn 68,250 KRW before tax, 57,739 KRW after tax, for a maturity payout of 3,657,739 KRW.

For 10,000,000 KRW at 3.5% for 12 months, interest before tax is 350,000 KRW simple and 355,670 KRW compound. Compound interest also earns interest on interest, so the gap widens with the term; compounding here is monthly.

Under standard taxation, 14% interest income tax plus 1.4% local income tax, 15.4% in total, is withheld from the interest. If financial income such as interest and dividends exceeds 20 million KRW a year it is taxed together with other income, so the real tax can differ.

For products whose interest is exempt from income tax when the conditions are met, such as a tax-free comprehensive savings account (for people aged 65 or over receiving the basic pension, disabled people, state-merit holders and similar, up to 50 million KRW across all institutions, open for new accounts until 31 December 2028). Reduced-rate options such as the 9.5% preferential rate are not offered, so compare the exempt and standard results.

The formula is the same, but interest paid at maturity or monthly, bonus rates, early-withdrawal rates, daily interest and rounding down to the won can shift the figure by a few won or more. Use it as a reference.

From 1 month to 600 months (50 years), in months or years. Switching the unit keeps the same term, so 24 months becomes 2 years.