Core concept
Compound growth makes prior returns part of the next return base
The calculator converts your annual return into a monthly rate and assumes contributions are added at the end of each month. Over time, accumulated contributions and returns both become part of the base for the next period.
Results separate the principal you contributed from the gain or loss under the compound assumption. When monthly contributions are included, the calculator shows future assets, principal, and compound gain or loss instead of a simple cumulative return.
Calculation methods
Choose the method that matches the values you know
Future assets
Given the initial investment, monthly contribution, annual return, and duration, see future assets, principal, and compound gain or loss.
Time to goal
Calculate how long it takes to reach a target amount. The result is the first whole month in which the goal is reached.
Required return
Given a duration and target amount, solve for the fixed annual return required. This does not predict future returns.
Required monthly contribution
Given an initial investment, duration, and annual return, calculate the minimum whole-KRW monthly contribution needed to reach the target.
Examples
The value to review depends on the question you are asking
Future assets
Estimated future assets: KRW 111,651,387
Initial KRW 10,000,000 · KRW 500,000 monthly · 8% annually · 10 years
Principal KRW 70,000,000 · compound gain KRW 41,651,387
Time to goal
Time required: 9 years 3 months
Initial KRW 10,000,000 · KRW 500,000 monthly · 8% annually · target KRW 100,000,000
The amount is below target at 110 months and reaches it at 111 months.
Required return
Required annual return: approximately +6.15%
Initial KRW 10,000,000 · KRW 500,000 monthly · 10 years · target KRW 100,000,000
This is solved using an assumed fixed annual return.
Required monthly contribution
Minimum monthly contribution: KRW 435,315
Initial KRW 10,000,000 · 8% annually · 10 years · target KRW 100,000,000
This is the minimum whole-KRW amount that reaches the target using the displayed contribution.
Before using the result
Results are reference values based on fixed assumptions
- The entered effective annual return is converted to a monthly rate that produces the same annual result and is assumed to remain constant throughout the period.
- The same contribution is added at the end of each month, and all returns remain invested.
- Results are nominal and exclude fees, taxes, inflation, exchange rates, dividends, and actual market fluctuations.
- General amounts are rounded to the nearest KRW. The required monthly contribution is rounded up to the minimum whole-KRW amount that reaches the goal. Results do not guarantee returns or recommend an investment decision.
Frequently asked questions
Does the annual return predict actual performance?
No. It is a fixed assumption supplied by you. Actual investment returns can vary every month, so the result should not be treated as a forecast or guarantee.
When is the monthly contribution added?
It is added at the end of each month. That month's new contribution therefore begins earning the assumed return in the following month.
Why is the time to goal shown in whole months?
Whole months keep the contribution timing consistent. The result is the first month in which the goal is reached; the balance remains below the goal in the preceding month.
Can I enter a negative return?
Future assets mode supports annual returns down to -100%. Time to goal, required return, and required monthly contribution use nonnegative return assumptions for reaching a goal.
Are taxes, fees, and inflation included?
No. This is a simplified model for understanding compound growth. Actual account results can differ because of costs, taxes, product characteristics, and market movements.
Related tools
Translate an asset goal into a price goal
After exploring a long-term asset goal, calculate the price required for a target return or profit on a position you already hold.