Savings Interest Calculator — Monthly Deposits and Net Returns
Compare lump-sum deposits and start-of-month savings with simple or monthly compound interest, estimated tax and net maturity amounts.
This calculator is for reference only and may differ from actual amounts due to law changes or individual circumstances. Please consult a licensed professional (tax accountant, labor attorney, etc.) for accurate calculations.
Use an initial deposit for money available today. Monthly deposits arrive at the START of each month. Set monthly deposits to zero for a lump-sum time deposit. The same timing is used for simple and monthly compound interest.
Example and limits
With no initial deposit, KRW 1 million at the start of each month, 4% a year and 12 months, simple interest is KRW 260,000 before tax: 1,000,000 × 0.04 ÷ 12 × (12+11+…+1). At 15.4% withholding, net interest is KRW 219,960.
Rates are illustrative, not current bank offers. This monthly model does not reproduce actual-day interest, early withdrawal penalties, changing rates, product eligibility or government contributions. Check the bank contract. Displayed amounts are rounded; actual withholding may differ. Inputs stay in this browser.
Deposit protection increased to KRW 100 million per depositor per covered financial institution from September 1, 2025, including covered principal and interest. Not every financial product is covered. Financial Services Commission
Frequently Asked Questions
Q. How do I distinguish a time deposit from monthly savings?
Use only the initial deposit for a lump sum. For monthly saving, set the initial deposit to zero and enter the installment. Entering both combines two separate cash flows.
Q. When do installments arrive?
At the start of every month. In a 12-month schedule, the first installment earns 12 months of interest and the last earns one month. Actual bank deposit dates may differ.
Q. What does monthly compounding mean?
Interest is added to the balance each month and earns interest thereafter. Simple interest accrues only on principal. Select the method specified in the product contract.
Q. Is the result tax-free by default?
No. The default assumes Korean interest withholding of 15.4%. Select exemption only if confirmed for your product and circumstances. Additional personal tax is not modeled.
Q. Are government contributions included?
No. Subsidized accounts depend on income, payments and retention conditions. Consult the product-specific bank calculation rather than treating them as ordinary deposits.
Q. What is the deposit protection limit?
Since September 1, 2025, covered principal and interest are protected up to KRW 100 million per depositor per covered financial institution. Verify that the product is covered.
How to Use
Enter money available today separately from future monthly payments.
Set the annual rate, term, interest mode and tax status.
Open the monthly breakdown and compare net amounts for the same payment schedule.
Worked example: Savings Interest Calculator — Monthly Deposits and Net Returns
KRW 12 million deposited for one year at 4% earns KRW 480,000 before tax. Twelve start-of-month payments of KRW 1 million earn KRW 260,000 with simple interest. The principal total is the same, but the holding periods are not. Compare cash availability before comparing quoted rates.
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