Investment Return Calculator
Forecast portfolio growth with regular contributions, expense ratios and inflation adjustment.
Portfolio Growth
How Investment Returns Compound
This calculator models the future value of an initial investment plus a stream of regular contributions, all growing at your assumed annual return, with expense ratios subtracted. The math is the same time-value-of-money formula used in every finance textbook: future value of a present sum plus future value of an annuity. Simple in concept, devastating in long-run effect — both for you (if you do it right) and against you (if you don't).
Same investor, two fund choices, 30 years apart
Imagine two investors, both starting with $10,000 and adding $500/month for 30 years. Both portfolios earn 8% gross returns. The only difference:
- Investor A picks a low-cost index ETF with a 0.05% expense ratio.
- Investor B picks an actively managed mutual fund with a 1.00% expense ratio.
| Investor | Net Return | Final Value | Fees Paid |
|---|---|---|---|
| A (index) | 7.95% | $760,000 | $8,000 |
| B (active) | 7.00% | $631,000 | $138,000 |
That 0.95% difference in annual fees costs Investor B $129,000 over 30 years — paid to the fund manager out of returns that would otherwise have been Investor B's. The active fund would need to consistently outperform the index by 0.95% per year just to break even, and the historical record shows that less than 15% of active funds beat their benchmarks over 15+ years. This is why low-cost index investing has become the default professional recommendation.
Why Fees Matter More Than People Realize
A 1% annual expense ratio doesn't sound bad. But it compounds destructively over decades because it's deducted from your total balance, not just from gains. In a year where the market returns 0%, the fee still applies. In a 30-year retirement portfolio, a 1% fee typically consumes 25-30% of the final balance.
Modern index ETFs charge 0.03-0.15%. Most workplace 401(k) plans have a few low-cost index options buried among more expensive default choices — check your plan's expense ratios.
Nominal vs Real Returns
Nominal returns are the raw growth number you see in marketing materials. Real returns subtract inflation, showing your actual increase in purchasing power. The distinction matters a lot for long-horizon planning:
| Asset Class | Nominal (long-run) | Real (after inflation) |
|---|---|---|
| U.S. stocks | ~10% | ~7% |
| International stocks | ~8% | ~5% |
| U.S. bonds | ~5% | ~2% |
| 60/40 portfolio | ~7-8% | ~4-5% |
| High-yield savings | ~3-5% | ~0-2% |
If you're saving for a future goal in today's dollars (retirement income, a kid's tuition), the real number is what matters. Plan with nominal returns if you're matching future-dollar goals (a $1M nominal target); plan with real returns if you're matching today-dollar goals (a $60k/year retirement income).
Dollar-Cost Averaging vs Lump-Sum Investing
If you have a large sum to invest (an inheritance, bonus, sale proceeds), should you invest it all at once or spread it out? Historical research from Vanguard and others consistently shows that lump-sum investing outperforms dollar-cost averaging about two-thirds of the time, because markets trend upward over long periods and time-in-market beats timing-the-market.
That said, DCA-ing a large sum over 6-12 months can be the right call psychologically — investing it all and then watching it drop 20% in a recession is the most common way people permanently bail out of investing. The marginal lower expected return is worth the higher probability of actually staying invested.
Reality check: Markets don't actually return a smooth 8% per year. The S&P 500 averages roughly 10% nominally, but in any given year you might get +30%, −20%, +5%, or anything in between. Volatility is real — and the only way the math actually works is if you stay invested through the bad years.
What's a Realistic Expected Return?
- 100% U.S. stocks: 7-10% nominal long-term
- Total world stock index: 6-8% nominal
- 60/40 stock/bond: 6-8% nominal
- All bonds: 3-5% nominal
- Cash / money market: 2-5% nominal (rate-dependent)
For a reasonable diversified portfolio assumption over 20+ years, use 7% nominal (4% real). Anything above 10% nominal in long-horizon planning ignores both the historical record and inflation.
The Three Levers That Actually Matter
If you want to maximize the final number this calculator produces, focus on:
- Time: Start as early as possible. A decade of head start is hard to outwork with extra contributions.
- Fees: Keep your expense ratios under 0.20%. Index funds win by default.
- Behavior: Don't sell during downturns. The math depends on staying invested through full market cycles.
Notice that "picking great stocks" isn't on this list. For 99% of people, low-cost index investing in a tax-advantaged account is the right strategy — and trying to outperform usually leads to underperformance.
Frequently Asked Questions
Does this account for taxes?
No — results are pre-tax. Real after-tax outcomes depend on account type (taxable, Traditional IRA/401k, Roth, HSA) and your tax bracket at withdrawal.
Should I use nominal or real return?
Either works as long as you're consistent. If you enter nominal return (e.g., 8%) and a 3% inflation rate, the calculator shows you both nominal and real values. If you want to plan in today's dollars throughout, use a real return (e.g., 5%) and set inflation to 0.
What about cryptocurrency?
Crypto has had exceptional but extremely volatile returns. Historical averages are meaningless because the asset class is so young. If you allocate to crypto, treat it as a high-risk satellite holding (~1-5% of portfolio), not a core retirement strategy.
Should I rebalance my portfolio?
Yes — periodic rebalancing (annually or when allocations drift >5% off target) maintains your intended risk level. Many platforms now do this automatically.
What's "sequence of returns risk"?
The risk that a string of bad years early in your investing period — or right after retirement — permanently damages portfolio outcomes. Diversification and bond allocation are the standard hedges.
How often should I check my portfolio?
Once a quarter is plenty for long-horizon investors. Daily checking is statistically a losing game — research shows people who check often trade more and underperform.