Investment calculator

How this projection works

This calculator compounds your starting balance and each monthly contribution forward using your expected annual return, applied monthly. Your initial amount compounds for the full period, while each new contribution starts compounding from the month it's added — so contributions made early in the timeline have more time to grow than ones made near the end.

Why the return rate matters so much

Small differences in expected return compound into large differences over long periods. A portfolio returning 5% versus 8% annually can produce a dramatically different final balance over 20-30 years, even with identical contributions — which is why it's worth using a conservative, realistic estimate rather than an optimistic best case.

What this doesn't account for

• Taxes on capital gains, dividends, or interest
• Investment fees or fund expense ratios
• Market volatility — real returns vary year to year rather than compounding smoothly
• Inflation eroding the purchasing power of the final balance

Return assumption	Typical use
3–4%	Conservative, bond-heavy portfolio
6–7%	Balanced stock/bond portfolio (long-term average)
8–10%	Aggressive, stock-heavy portfolio

Treat the result as a planning estimate, not a guarantee — past returns don't predict future performance.