A Practical Look at How Monthly Investing Builds Wealth Over Time

Compound interest is often referred to as the “eighth wonder of the world” — and for good reason.
Even small, consistent investments can grow into something surprisingly substantial over time, especially when compounded monthly.

In this post, we'll explore how investing just ₩100,000 per month over 10 years can grow, depending on different annual return rates: 5%, 8%, 10%, and 12%. We'll also break down how compounding frequency influences your total return.

This isn’t just theory — this is what smart, everyday investing can look like in real life.

 

Compound Interest

Scenario: Monthly Investment of ₩100,000 for 10 Years

Let’s assume you invest ₩100,000 at the end of every month for 10 years.
That’s a total principal of ₩12,000,000 over 120 months.

Compound interest is calculated using this formula:

A = P × ((1 + r)^n - 1) / r
 

1. At 5% Annual Return

  •  Total Investment: ₩12,000,000
  •  Total Value After 10 Years: ≈ ₩15,910,000
  •  Interest Earned: ≈ ₩3,910,000

 

Even at a modest return of 5%, your investment grows by nearly 33% thanks to compounding.

2. At 8% Annual Return

  •  Total Investment: ₩12,000,000
  •  Total Value After 10 Years: ≈ ₩18,510,000
  •  Interest Earned: ≈ ₩6,510,000

 

8% mirrors the long-term average return of the Korean stock market — making this a realistic expectation for balanced investors.

3. At 10% Annual Return

  •  Total Investment: ₩12,000,000
  •  Total Value After 10 Years: ≈ ₩20,480,000
  •  Interest Earned: ≈ ₩8,480,000

 

10% is close to the historical average of the S&P 500.
Here, your earnings are over 70% of the original capital, showing how early exposure and compounding amplify returns.

Compound Interest

 

4. At 12% Annual Return

  •  Total Investment: ₩12,000,000
  •  Total Value After 10 Years: ≈ ₩23,000,000
  •  Interest Earned: ≈ ₩11,000,000

 

In high-performing portfolios, a 12% return is ambitious but not impossible.
Here, the interest alone nearly doubles your investment.

Bonus: How Compounding Frequency Affects Growth

Let’s say you invest ₩1,000,000 for 1 year at 10% annual return:

Compounding Type Final Amount
Annual ₩1,100,000
Quarterly ₩1,103,800
Monthly ₩1,104,700
Daily ₩1,105,200

This is especially powerful when you're contributing regularly.

Real-Life Insight: What I Learned From 10 Years of Monthly Investing

I personally started investing ₩100,000 per month in 2013.
Back then, I thought it was too small to matter. But fast forward 10 years, and here’s what I’ve learned:

Consistency — not timing — was the biggest factor.

Compound Interest

 

Final Thoughts: Compound Interest Rewards Patience

Whether you earn 5% or 12%, the discipline of investing regularly beats trying to time the market.

If you start today with ₩100,000 per month:

  •  At 5%: You'll likely have ≈ ₩15.9M
  •  At 10%: You'll be close to ₩20M
  •  At 12%: You could hit ₩23M or more

 

The longer you wait, the more you miss out on the magic of compounding.
Start small, stay consistent, and let time do the heavy lifting.

 

DCA vs. Lump-Sum Investing: Which Strategy Wins in the Long Run?
Investment ROI Simulator

 

 

 

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