How does compounding frequency affect returns?

More frequent compounding produces slightly higher returns. On $10,000 at 10% for 10 years: annual compounding → $25,937; monthly → $27,070; daily → $27,180. The difference grows larger over longer periods and at higher rates.

What is the Rule of 72?

The Rule of 72 is a quick way to estimate how long it takes to double your money: divide 72 by the annual interest rate. At 6%, your investment doubles in 12 years. At 9%, in 8 years. At 12%, in just 6 years.

What annual return is realistic for long-term investing?

Global equity index funds (S&P 500, MSCI World) have historically returned 7-10% annually over 20+ year periods. Bonds: 3-5%. High-yield savings: 4-5% currently. CD/term deposits: 4-5%. Always account for inflation (2-3%) when comparing real returns.

Why do monthly contributions matter so much?

Regular contributions dramatically accelerate growth. Starting with $0 and contributing $300/month at 7% for 30 years yields $340,000. Starting with $10,000 but contributing nothing yields only $76,000. Consistency beats initial capital for long-term wealth building.

Compound Interest Calculator

Calculate how your investment grows with compound interest. See the power of regular contributions and time on long-term wealth building.

📈Compound Interest Calculator

Initial Investment

Monthly Contribution

Annual Rate (%)

Period (years)

years

Compounding Frequency

About this calculator

The compound interest calculator shows exactly how your investment grows over time, factoring in initial capital, regular monthly contributions, annual interest rate, and compounding frequency. It is the essential tool for long-term financial planning. The formula for compound interest with regular contributions is: FV = P(1+r/n)^(nt) + C[(1+r/n)^(nt)−1]/(r/n), where P is the principal, r the annual rate, n the compounding frequency, t the years, and C the periodic contribution. The growth chart makes the exponential "snowball effect" visually clear. Use this calculator to: plan retirement savings, evaluate the impact of starting earlier vs contributing more, compare investment products by their projected returns, or understand the long-term cost of inflation. Time is the most powerful variable in compound interest — even a few extra years dramatically changes the outcome.

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Frequently Asked Questions

Compound interest is interest earned on both the initial principal and the previously accumulated interest — "interest on interest." With $10,000 at 7% for 30 years, compound interest produces $76,122 vs $31,000 with simple interest. This exponential growth is why starting early matters so much.