Retirement Calculator
Free retirement calculator. Project how current savings and monthly contributions grow to retirement age, with inflation-adjusted values. No signup.
A retirement calculator projects what a current balance plus regular monthly contributions will grow to by retirement age. It reports the nominal future value, the same figure in today’s dollars after inflation, total contributions, investment growth, and a rough monthly income the balance could support. At the defaults — $10,000 now, $500 a month, 7% a year, retiring at 65 from age 30 — it projects about $1,015,589 nominal, or roughly $427,940 in today’s purchasing power.
How the projection is calculated
Returns compound monthly. Let r be the annual return divided by 12 and n the number of months to retirement. The calculator runs three formulas:
- Growth on the starting balance: balance × (1 + r)n
- Growth on contributions: monthly × ((1 + r)n − 1) ÷ r, assuming each contribution lands at the end of the month
- Future value: those two amounts added together
It then deflates the result by inflation to get today’s purchasing power (future value ÷ (1 + inflation)years) and estimates a monthly retirement income by treating the balance as a 30-year annuity at the same return: future value × r ÷ (1 − (1 + r)−360).
Worked example with the default inputs
Starting age 30, retirement age 65, so n = 35 × 12 = 420 months and the monthly rate is 7% ÷ 12 = 0.5833%.
| Step | Calculation | Result |
|---|---|---|
| Starting balance grows | $10,000 × (1.005833)420 | $115,062 |
| Contributions grow | $500 × ((1.005833)420 − 1) ÷ 0.005833 | $900,527 |
| Future value | $115,062 + $900,527 | $1,015,589 |
| Total contributed | $10,000 + $500 × 420 | $220,000 |
| Investment growth | $1,015,589 − $220,000 | $795,589 |
| Inflation-adjusted | $1,015,589 ÷ (1.025)35 | $427,940 |
| Est. monthly income (30 yr) | $1,015,589 × 0.005833 ÷ (1 − (1.005833)−360) | $6,757 |
Only $220,000 of the final balance is money you put in; the remaining $795,589 is compound growth. Note that the inflation-adjusted figure is less than half the nominal one — that gap is why a “million dollars” in 35 years is not a million dollars of today’s spending.
What $500 a month becomes at 7%
Stripping out the starting balance isolates the contribution effect. The table below compounds a single $500 monthly contribution at 7% for different horizons.
| Years | Future value | You contributed | Growth |
|---|---|---|---|
| 10 | $86,542 | $60,000 | $26,542 |
| 20 | $260,463 | $120,000 | $140,463 |
| 30 | $609,985 | $180,000 | $429,985 |
| 40 | $1,312,407 | $240,000 | $1,072,407 |
Growth overtakes contributions somewhere between the 20- and 30-year marks. That crossover is the argument for not delaying.
Common mistakes
- Using a return rate you cannot defend. Long-run broad-market assumptions usually sit around 7–10% nominal before fees. A 12% input flatters the result.
- Forgetting fees. If your fund charges 1% a year, enter 6% rather than 7%.
- Planning on the nominal figure. Retirement spending happens in future dollars, so the inflation-adjusted number is the one to compare against a target.
- Ignoring other income. The monthly-income estimate is only from this pot; add any pension or government benefit separately.
What rate of return should I enter?
Use a number you can justify from long-run asset-class returns, then subtract your fund’s expense ratio. A 60/40 stock-and-bond mix has historically returned less than an all-stock allocation, so match the rate to your actual portfolio rather than copying a headline figure.
Does the calculator account for taxes?
No. Contributions may be pre- or post-tax depending on the account type, and withdrawals are taxed differently. The projection is a compounding estimate before tax; reduce your effective return or expected income if you want a rough tax adjustment.
Why is the estimated monthly income higher than I expected?
The income figure assumes the entire balance keeps earning the same return while you withdraw over 30 years. If you retire earlier, hold a more conservative portfolio, or want the balance to last longer, your sustainable withdrawal will be lower.
How much can I safely withdraw each year?
The estimated monthly income assumes the balance is fully spent over 30 years. A more conservative planning approach is the 4% rule, which withdraws about 4% of the starting balance in year one and adjusts that amount for inflation thereafter, aiming to preserve the pot beyond 30 years. On this balance, 4% is roughly $40,624 a year, or about $3,385 a month — noticeably less than the $6,757 the depletion model shows, because leaving a buffer guards against a long retirement and poor early returns.
Because the same compounding math drives both, the investment growth calculator is a useful cross-check when you already hold a lump sum. If you are deciding whether to invest or clear debt first, compare the return here with the rate on the simple loan calculator.