Investment Calculator
Project both the growth and the drawdown of your portfolio. Pick a preset (S&P 500, NASDAQ, 60/40, bonds) or enter your own return, then see what it supports in retirement.
Last verified · Methodology
How to Use This Calculator
Set the Growth Phase
Enter your starting balance, monthly contribution, and how many years you plan to invest. Pick a preset that matches your portfolio mix.
Turn on Withdrawal (optional)
Toggle the withdrawal phase to see how long your money lasts once you start drawing it down. Keep 'adjust for inflation' on to preserve real purchasing power.
Read the Outlook
A green check means your portfolio lasts the full horizon. An amber warning means you need to cut the monthly draw or extend the growth phase.
Historical Returns by Asset Class
Long-run averages. Past performance does not guarantee future results, but these are useful priors.
| Asset / Portfolio | Nominal Return | After 3% Inflation | Risk Profile |
|---|---|---|---|
| NASDAQ 100 | 11.0% | 7.8% | High volatility |
| S&P 500 | 10.0% | 6.8% | Moderate to high |
| 60/40 Portfolio | 7.0% | 3.9% | Moderate |
| Corporate Bonds | 5.0% | 1.9% | Low to moderate |
| US Treasury Bonds | 4.0% | 1.0% | Very low |
| High-Yield Savings | 4.5% | 1.4% | Zero (insured) |
Compounding: Small Differences, Big Outcomes
What a $500/mo contribution becomes after 30 years at different return rates, starting from $0:
| Annual Return | Total Contributed | Final Balance | Multiple on Money |
|---|---|---|---|
| 4% | $180,000 | $347,000 | 1.9x |
| 7% | $180,000 | $611,000 | 3.4x |
| 10% | $180,000 | $1,139,000 | 6.3x |
| 11% | $180,000 | $1,404,000 | 7.8x |
The gap between 7% and 10% is not 3%, it is $528,000. Low-cost index funds and minimizing fees is how you capture the full market return instead of leaking it to costs.
| Annual Return | 10 Years | 20 Years | 30 Years |
|---|---|---|---|
| 5% | $78,000 | $206,000 | $416,000 |
| 7% | $87,000 | $262,000 | $567,000 |
| 8% | $91,000 | $294,000 | $680,000 |
| 10% | $102,000 | $378,000 | $1,030,000 |
Historical averages: the S&P 500 has returned roughly 10% annually before inflation and about 7% after inflation over the long run (1926 to 2024). The NASDAQ 100 has averaged closer to 11%. A balanced 60/40 stock/bond portfolio averages around 7%, while US Treasury bonds average about 4%. High-yield savings currently pays 4% to 5%. Use the preset that matches your actual allocation.
Nominal is the raw percentage your portfolio grows. Real is nominal minus inflation, the growth in your actual purchasing power. Example: if your portfolio returns 10% in a year when inflation is 3%, your real return is roughly 7%. The calculator shows both your nominal final balance and its value in today's dollars.
After your accumulation period ends, the calculator treats your final balance as the starting point and simulates monthly withdrawals while the remainder continues to earn returns. If you enable 'adjust for inflation,' your withdrawal amount increases each year so you keep the same purchasing power. The calculator tells you if the money lasts the full horizon and what the safe sustainable withdrawal would be.
A retirement withdrawal guideline: withdraw 4% of your starting portfolio in year one, then adjust that dollar amount for inflation each year after. Historical backtests show this works for a 30-year retirement in most periods. On a $1 million portfolio, that is $40,000/yr or about $3,333/mo. The calculator's 'safe monthly' value is similar in concept but computed directly from your inputs.
Yes. Treat your combined retirement accounts (401k, Roth IRA, Traditional IRA, taxable brokerage) as one total. Include employer match in your monthly contribution. The calculator does not distinguish between account types, but the math is the same. If you want to model taxes on Traditional 401k withdrawals, reduce the withdrawal amount by your expected marginal tax rate.
This calculator assumes steady returns every year. In reality, markets are volatile and a major crash in your first retirement years hurts much more than the same crash later (because you draw down a shrunk portfolio). To be conservative, use a return assumption 1 to 2 percentage points lower than historical averages, or keep 2 to 3 years of expenses in cash to weather downturns without selling.
A $4,000/mo lifestyle today requires roughly $7,244/mo in 30 years at 2% inflation, or $17,449/mo at 5% inflation. If you do not adjust withdrawals upward, your real spending power shrinks every year. Always enable the 'adjust for inflation' option unless you specifically want to see nominal (fixed-dollar) drawdown.
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