Compound Interest & Savings Calculator

How it works

• The annual return is converted to a monthly rate ((1+r)^1/12−1); contributions are made at the end of each month.
• In Korea, interest and dividends are taxed at 15.4% (withheld); ISA and pension accounts can reduce this.
• Investment returns are not guaranteed.

FAQ

What is the rule of 72?

Divide 72 by the annual return (%) to estimate how many years it takes to double. At 6%, about 12 years.

How is interest taxed in Korea?

Interest income is taxed at 15.4% (14% national + 1.4% local), withheld at source.

Worked example

Example: starting with ₩10 million and adding ₩500,000 a month at 6% for 10 years turns ₩70 million of contributions into about ₩99.1 million — a profit of about ₩29.1 million, or 41.6% cumulative.

Time matters more than the rate: ₩10 million left alone at 6% grows to about ₩17.9 million in 10 years, and monthly contributions of ₩500,000 add ₩60 million of principal on top. Starting five years earlier usually adds more than chasing a slightly higher return. Use the target tab to see how much you need to save each month to reach a goal such as ₩100 million.

Common mistakes

• A 6% return is not guaranteed; equity funds can lose money in some years.
• In a regular Korean account, interest and dividends are taxed at 15.4%; ISA and pension accounts are taxed less.
• Fund fees of 0.1–1% a year compound too and can reduce the result noticeably.
• Money in 10 years buys less than today; use the inflation calculator for real value.
• Withdrawing early breaks the compounding chain.

Explanation checked on 2026-10-30 · Spotted an outdated value? Tell us