Compound Interest & SIP Calculator

Project the exponential growth of your wealth over time through disciplined investing and compound returns.

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Estimated Total Wealth
$214,892

Amount Invested
$95,000

Compound Gains
+$119,892

Invested: 44%
Wealth Gain: 56%

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The Power of Compound Interest & Systematic Investing

Albert Einstein famously called compound interest the “eighth wonder of the world: he who understands it, earns it; he who doesn’t, pays it.” In personal finance, compounding turns modest monthly contributions into substantial multi-million dollar portfolios over time.

The Compound Interest Mathematical Formula

Our calculator combines the future value of a lump sum principal with the future value of a monthly compounding annuity (SIP):

FV = [P × (1 + r/n)ⁿᵗ] + [PMT × (((1 + r/n)ⁿᵗ - 1) ÷ (r/n))]

The Power of Compound Interest & Systematic Investing (SIP)

Compound interest is often called the eighth wonder of the world because your money generates returns on both your original principal and your accumulated interest. Over long investment horizons (10, 20, or 30 years), the compounding effect exponentially accelerates wealth accumulation.

The Compound Interest Formula Explained

Our calculator computes future wealth using the standard discrete compound interest equation with regular monthly contributions:

A = P × (1 + r/n)^(n×t) + PMT × [((1 + r/n)^(n×t) – 1) / (r/n)]

Where P is starting principal, r is annual interest rate (decimal), n is compounding frequency (12 for monthly), t is time in years, and PMT is recurring monthly contribution.

Frequently Asked Questions (FAQ)

What is a realistic annual rate of return to assume for stock index funds?

Historically, broad-market index funds like the S&P 500 have generated average annualized nominal returns of approximately 10% before inflation (or 7% after factoring in inflation) over rolling 30-year windows.

How does monthly compounding differ from annual compounding?

Monthly compounding calculates and reinvests returns 12 times per year instead of once. Because earned interest starts generating returns immediately the following month, monthly compounding results in slightly higher total yields over time.

Is systematic monthly investing (SIP) better than lump-sum investing?

Dollar-cost averaging via recurring monthly deposits helps eliminate emotional timing mistakes by automatically buying more shares when asset prices dip and fewer when markets are elevated, reducing overall portfolio volatility.