📈 How Investment Growth Works (Lump Sum vs Monthly Contributions)

A single lump sum invested today and a steady stream of monthly contributions both grow through compounding — but they grow differently, and most real investment plans actually use both at once: an initial amount, plus regular ongoing contributions on top.

How a Lump Sum Grows

Money invested as a single lump sum starts compounding immediately on the full amount. Every year (or month, depending on compounding frequency) it earns a return, and that return itself starts earning a return the next period — the classic compound growth curve, starting slow and accelerating over time.

How Monthly Contributions Add Up

Adding a fixed amount every month works differently: each contribution starts compounding from the moment it's added, so contributions made early in the investment period have far more time to grow than contributions made near the end. The last few months of contributions barely have time to earn anything before the end date — but they still add their full value to the total.

Why Combining Both Compounds Faster

Why Starting Early Beats Contributing More

Because of how compounding works, time in the market matters more than the exact contribution amount for long time horizons. A smaller amount invested a decade earlier can end up larger than a bigger amount invested later, simply because it had more compounding periods to grow.

Compounding Frequency Still Matters

Just like with interest, how often returns compound — monthly, quarterly, or annually — changes the final result slightly, with more frequent compounding producing marginally higher growth at the same stated annual return.

Step-by-Step: Project Your Investment

1. Enter your initial investment (lump sum, if any)
2. Enter your planned monthly contribution
3. Enter your expected annual return and investment period
4. Choose a compounding frequency and review your projected future value