Korean Savings & Deposit Interest Calculator

A term deposit earns interest on the whole sum from the start; a monthly savings plan (jeokgeum) earns interest on each deposit only for the months it stays in. At the same rate a savings plan therefore pays a little over half as much. Simple interest on a savings plan is monthly amount × annual rate ÷ 12 × n(n + 1) ÷ 2: 1,000,000 won a month for 12 months at 4% earns 1,000,000 × 4% ÷ 12 × 78 = 260,000 won. The same 12,000,000 won deposited at the start would earn 480,000 won simple.

Korean banks withhold 15.4% of the interest (14% income tax plus 1.4% local income tax). On the savings plan above that is 40,040 won, leaving 219,960 won of interest and 12,219,960 won at maturity. Preferential-tax products withhold 9.5%, and tax-free products nothing. Monthly compounding adds interest on interest each month, so it pays slightly more than simple.

Banks differ in day counting, bonus-rate conditions and early-closure rates, so the real figure can be a few won to a few tens of won off. The headline rate usually assumes every bonus condition is met, so also try the base rate.