Savings Interest Calculator
Work out gross interest, the withholding tax and the after-tax payout for a lump-sum deposit or a monthly savings plan, on simple or compound interest.
How to use
- Choose the product type: a lump-sum deposit or a monthly savings plan.
- Choose simple or compound interest. Compound here means interest added to the principal every month.
- Enter the annual interest rate and the term — months or years — or tap a preset such as 12 or 24 months.
- Enter the principal for a deposit, or the amount you pay in each month for a savings plan, then pick the tax treatment.
- Gross interest, withholding tax, after-tax interest and the maturity payout appear instantly, broken down in the table.
FAQ
What is the difference between a deposit and a savings plan?
A lump-sum deposit puts the whole amount in at once and pays interest on all of it at maturity. A monthly savings plan pays in the same amount every month, so each deposit earns interest for a different number of months and the first one earns the most.
How do simple and compound interest differ?
Simple interest is charged on the principal only. Compound interest is also charged on the interest already earned, so it always pays more and the gap widens with the term.
Why is the interest on a savings plan smaller than the total paid in?
Because the money arrives month by month — the final deposit only earns one month of interest. The calculation therefore weights every deposit by its own term, using n(n+1)÷2 over n months.
How much tax is withheld?
Under standard taxation, 14% interest income tax plus 1.4% local income tax — 15.4% in total — is withheld from the interest. Tax-exempt products only qualify when their conditions are met, so check the product sheet.
Will this match my bank statement exactly?
The formula is the same, but interest paid at maturity or monthly, bonus rates, early-withdrawal rates and rounding to the won can shift the figure by a few won. Use it as a reference.
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