Investment Calculator
Project your investment growth and plan your financial future
Results & Details
// Return Rate Comparison
Year-by-Year Breakdown
| Year | Contributions | Gains | Total Invested | Balance |
|---|---|---|---|---|
| 📈 Calculate above to see yearly growth | ||||
How to Use the Investment Calculator
Enter your initial lump sum investment, monthly contribution amount, expected annual return rate, and investment period. You can also enter an inflation rate to see what your future balance is worth in today's money — known as the inflation-adjusted or "real" value.
Investment Type Presets
Use the tabs above to load typical return rate defaults for different asset classes. Stock market investments have historically averaged around 7–10% annually over the long term. Bonds typically return 3–5%. Savings accounts currently yield 4–5% in many countries. Use the Custom tab to enter any rate you like.
How Returns Are Calculated
What Return Rate Should I Use?
Historical averages by asset class (nominal, before inflation): global stock markets 7–10%, bonds 3–5%, real estate 6–8%, high-yield savings 4–5%, cash/money market 2–4%. Past performance does not guarantee future results.
Why Include Inflation?
Inflation erodes purchasing power over time. At 3% inflation, £100 today buys what £74 buys in 10 years. The inflation-adjusted value in this calculator shows what your future balance is worth in today's money — giving you a more realistic picture of your real wealth.
Projecting Investment Growth Honestly
Built and verified by Andrius R. · Updated June 2026
Every investment projection is built from four inputs — starting amount, contributions, return rate, and time — plus two quiet saboteurs most calculators ignore: inflation and fees. Here's how to set each input so the output means something.
A full worked example, nominal vs real
| Scenario | Rate used | Value after 25 years |
|---|---|---|
| Nominal (headline) projection | 7% | ~$219,300 |
| Real (inflation-adjusted, ~2.5%) | 4.5% | ~$141,300 |
Total contributed: $70,000 either way. Both numbers are "true" — but the second one is in today's buying power, which is the one your future self actually spends. Decide which view you're using before reading any projection, and never mix them.
Fees: the difference compound interest works against you
Fund fees come out of returns before you see them, so they compound too. Same example, 7% gross market return:
| Annual fund fee | Value after 25 years | Cost of the fee |
|---|---|---|
| 0.1% (typical index fund) | ~$215,300 | — |
| 1.0% (typical active fund) | ~$183,200 | ~$32,100 |
A 0.9-point fee difference quietly consumed about 15% of the final portfolio. This — combined with the fact that most active funds underperform their index over long periods anyway — is why fee minimization is one of the few guaranteed wins in investing.
What return rate is honest to assume?
Broad US stock indexes have returned roughly 10% per year nominal (≈7% real) averaged over the past century — averaged being the key word, hiding individual years from −37% to +38%. Bonds have returned far less; cash less still. Sensible practice: use 6–7% nominal (or 4–5% real) for a diversified stock-heavy portfolio, lower if you hold bonds, and always run a pessimistic case 2 points lower. If a plan only works at 10%+, it isn't a plan — it's a hope.
Sequence matters more than average near the finish line
Two investors can earn the same average return and end with very different outcomes if the bad years land at different times. Crashes early in your accumulation years are actually a gift (you buy cheap for decades); the same crash in the first years of withdrawal can permanently damage a retirement portfolio — "sequence of returns risk." It's the core reason retirement portfolios shift toward bonds with age, and a major caveat on any straight-line projection, including this calculator's.
The behaviors that beat the math
Time in the market beats timing the market: missing just the handful of best single days in a decade — which tend to cluster right next to the worst days — cuts long-run returns dramatically, which is the statistical case against jumping in and out. The boring playbook wins: automate contributions, buy broad low-fee index funds, ignore the noise, and let the compounding math do what it does. Your projected curve above assumes you stay invested; the biggest risk to it is usually the investor, not the market.
From the Blog
// Time in Market
Time in the market beats timing the market. Starting early is the single most powerful investment decision you can make.
// Diversify
Spreading investments across asset classes (stocks, bonds, real estate) reduces risk without necessarily reducing returns.
// Fees Matter
A 1% annual fee can reduce your final balance by 20–30% over 30 years. Always check expense ratios on funds.
// Real Returns
Subtract inflation from your return rate to get your real return. 8% nominal at 3% inflation = ~5% real growth.