Simple Investment Calculator

Enter a starting balance, contribution amount, time horizon, and expected return — get a projected final balance, milestone table, and money-weighted IRR. Toggle on inflation adjustment to see results in today's dollars.

Inputs

%

Enter the nominal (pre-inflation) rate.


Need a more detailed analysis?

This calculator uses simplified inflation math and does not adjust contributions for rising prices. For a more thorough model — one that treats contributions in today's dollars and shows purchasing power year by year — use the Inflation-Adjusted Investment Calculator.

Assumes contributions happen at the end of each period and growth compounds once per contribution period.

Final balance
$—
Total capital invested
$—
Growth from returns
$—
IRR (money-weighted, annualized)

Balance at milestones

Year Total contributed Balance

Assumptions

  • Compounding: per contribution period
  • Contributions: end of each period
  • Fees: none modeled
  • Taxes: not modeled

Educational estimates only. Real-world outcomes vary with fees, taxes, and return volatility.

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Frequently Asked Questions

What is the difference between nominal and real returns?

A nominal return is the raw percentage gain on an investment, before accounting for inflation. A real return adjusts for inflation, showing how much your purchasing power actually grew. If your portfolio returns 7% in a year when inflation runs at 2.5%, your real return is approximately 4.4% — the rest is offset by rising prices.

Over long time horizons, the gap between nominal and real returns compounds into a significant difference in buying power. The Inflation: The Math That Makes Future Money Smaller article works through the arithmetic in detail.

What does "inflation-adjusted" mean in this calculator?

When real mode is enabled, the calculator converts your nominal expected return to a real return using the Fisher equation: real = (1 + nominal) ÷ (1 + inflation) − 1. It then uses that real rate for compounding, so the final balance is expressed in today's purchasing power rather than future nominal dollars.

One important limitation: this calculator does not automatically adjust your contribution amounts for inflation. If you contribute $500/month today and inflation runs at 2.5%, a truly inflation-neutral model would increase contributions each year to maintain the same real saving effort. The Inflation-Adjusted Investment Calculator handles this correctly and should be used for any analysis where that distinction matters.

Why does inflation adjustment matter over long horizons?

Inflation compounds silently alongside your investment returns. Over 25 years, even a moderate 2.5% annual inflation rate roughly halves purchasing power — meaning a $1,000,000 nominal balance may only buy what $540,000 buys today. The longer the time horizon, the larger this gap becomes, and the more misleading it is to plan using nominal figures alone.

You can explore how inflation has varied historically using the Historical Inflation Rates (CPI) tool, or use the Inflation Time Machine to convert a specific dollar amount between two years.

How is the money-weighted IRR calculated?

The money-weighted IRR (Internal Rate of Return) is derived from the actual cash flows: your starting deposit (an outflow at time zero), each recurring contribution (outflows at the end of each period), and the final projected balance (an inflow at the end). The calculator solves for the annualized discount rate that makes the net present value of all those cash flows equal to zero.

Unlike a simple average return, the IRR accounts for the timing and size of each contribution — so it reflects what your money actually earned, weighted by when it was invested. For most straightforward scenarios with constant contributions, the IRR will be close to (but not identical to) the expected return you entered.

What assumptions does this calculator make?

This calculator assumes a constant expected return (no volatility or sequence-of-returns risk), fixed contribution amounts throughout, contributions occurring at the end of each period, compounding once per contribution period, and no fees or taxes. When real mode is enabled, it also assumes a constant inflation rate.

These are simplified assumptions appropriate for first-pass estimates. Fees in particular can compound into a substantial drag over long horizons — the fee calculators quantify that impact explicitly. Taxes depend on account type: returns inside a TFSA are tax-free, while a taxable account will reduce effective returns depending on the type of income generated.

How does compounding frequency affect results?

This calculator compounds returns once per contribution period — so monthly contributions compound monthly, and annual contributions compound annually. More frequent compounding produces slightly higher balances than less frequent compounding at the same nominal annual rate, because each period's growth is itself reinvested sooner.

For a transparent look at how compounding multipliers work at different rates and horizons, see the Compound Interest Multipliers Table. For a deeper explanation of the compounding mechanic itself, see Compound Interest: The Ultimate Wealth Builder.

Disclaimer: All content on The Long Math — including articles, essays, calculators, tools, or any other material — is provided solely for educational and informational purposes and does not constitute financial, tax, legal, or investment advice. Any results or projections are based on simplified models, assumptions, and user-supplied inputs and may not reflect real-world outcomes. You are responsible for evaluating the accuracy and applicability of the information provided and for conducting your own due diligence. Before making financial decisions, consult a qualified professional.