Investment Calculator

Solve for the end balance, contribution amount, return rate, starting amount, or investment length of a growing investment with regular contributions.

of each

Why the same four numbers keep showing up

Every investment plan is a relationship between a starting amount, regular contributions, a return rate, and time. Change any one of them and the end balance shifts — sometimes dramatically. This calculator flips the usual question around: instead of always asking "how much will I have?", it can just as easily answer "how much do I need to contribute?" or "what return do I actually need?" to hit a specific target.

Why compounding frequency matters less than people think

The difference between monthly and daily compounding at the same stated rate is real but small — a few dollars on a typical account, not a few thousand. What actually moves the end balance is the rate itself, how long the money compounds, and how much gets added along the way. Don't let a compounding-frequency choice distract from the much bigger levers: starting earlier, contributing more, or seeking a genuinely higher (and appropriately risk-adjusted) return.

Contributing at the beginning of each period instead of the end means every contribution earns one extra period's worth of growth — a small-sounding difference that adds up meaningfully over a long investment horizon.

Common questions

What return rate should I assume?

This calculator doesn't predict future returns — it just does the math for whatever rate you plug in. Many long-term investors use a long-run historical average for the asset class in question as a starting estimate, while remembering that past returns never guarantee future ones.

Why does "Return Rate" solve for an annually-compounded rate?

It's reported as the effective annual rate regardless of how often you compound or contribute, so you can compare it apples-to-apples against other investments quoted the same way.

Does this account for taxes or fees?

No — it models gross growth only. Taxes on gains and any account or fund fees would reduce the real end balance below what's shown here.

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