Savings Interest Calculator
About this tool
Calculated the way Korean banks do. Simple-interest deposits earn principal × rate × months ÷ 12; installment savings earn interest only for the months each payment is in, so monthly × rate ÷ 12 × n(n+1)/2. Monthly compounding also earns interest on past interest.
Saving 1,000,000 won a month at 3.5% for 12 months gives 12,000,000 won principal and 227,500 won pre-tax interest; after the standard 15.4% tax, 12,192,465 won. That is why a 3.5% savings rate returns only about 1.9% of the total principal.
Choose standard tax 15.4% (14% income tax + 1.4% local tax), preferential 9.5% or tax-free. Amounts are rounded down to the won.
FAQ
Why is savings interest lower than expected?
The first payment earns 12 months of interest but the last earns only one, so on average about half the principal earns a full year.
What is the 15.4% tax?
14% interest income tax plus 1.4% local income tax (10% of the income tax).
Can results differ from my bank?
Slightly — banks may use daily calculation or different rounding.