Investment Calculator

Project what a portfolio could grow to with regular contributions and an expected annual return, and see what that balance would be worth in today's dollars after inflation.

For example, 3% if you raise your contribution in line with pay rises.

An average yearly return after fund fees. Actual returns vary from year to year.

Used to show the balance in today's dollars. Enter 0 to skip.

Ending balance
$445,795.27
In today's dollars
$240,457.77After 2.5% yearly inflation
Total contributed
$160,000.00Starting amount plus all contributions
Investment growth
$285,795.27
Real (after-inflation) annual return
4.39%
  • Assumes the same return every year. Real markets rise and fall, so the actual path and ending balance will differ.
  • Ignores taxes. In a taxable account, dividends and realized gains are taxed along the way; in a 401(k) or IRA, growth is tax-deferred or tax-free.

Year by year

YearContributed this yearGrowth this yearBalanceBalance in today's dollars
1$6,000.00$890.15$16,890.15$16,478.19
2$6,000.00$1,372.46$24,262.61$23,093.50
3$6,000.00$1,888.53$32,151.14$29,855.53
4$6,000.00$2,440.73$40,591.87$36,774.23
5$6,000.00$3,031.58$49,623.45$43,859.90
6$6,000.00$3,663.79$59,287.24$51,123.20
7$6,000.00$4,340.26$69,627.49$58,575.19
8$6,000.00$5,064.07$80,691.56$66,227.32
9$6,000.00$5,838.56$92,530.12$74,091.49
10$6,000.00$6,667.26$105,197.38$82,180.02

How this projection works

The calculator starts with your current amount, adds each contribution, and grows the whole balance at your expected annual return. Monthly contributions grow at the monthly rate that compounds to your annual return, so a 7% return means exactly 7% over a full year. If you raise your contributions every year, each year's contribution is the previous year's plus that percentage.

The second figure, in today's dollars, divides the ending balance by the growth in prices over the period at your inflation rate. It answers a more useful question than the headline number: what that future balance will actually buy, measured in money you understand today.

Choosing a return and an inflation rate

No one can promise an investment return. Stocks have historically returned more than bonds or cash over long periods, but with large swings and long stretches of losses; bonds and cash are steadier and lower. A diversified portfolio's return sits somewhere in between depending on its mix. Use the return after fund fees, because a 1% annual fee comes straight off the rate you enter.

Run more than one scenario. A cautious rate and an optimistic rate give you a range, which is more honest than a single number. For inflation, the Federal Reserve targets 2% a year over the longer run; actual inflation has been well above and below that at different times.

Why contributions and time matter more than the return

Over 25 years, raising contributions by 3% a year turns $500 a month into a balance about $124,000 larger in the example below, without needing a higher return. Time works the same way: the last few years of a long plan often add more growth than the first ten combined, because they compound on the largest balance.

Sequence matters too. Two investors with the same average return can end with different balances if one suffers big losses near the end, when the balance is largest. That risk is why many people shift toward steadier investments as they approach the date they need the money.

The formula

Balance = P × (1 + R)^t + C × ((1 + i)^N − 1) ÷ iToday's dollars = Balance ÷ (1 + inflation)^tReal return = (1 + R) ÷ (1 + inflation) − 1
  • P = starting amount, C = contribution each period (level contributions)
  • R = expected annual return, t = years
  • i = return per period = (1 + R)^(1/12) − 1 for monthly contributions
  • N = number of contributions. With yearly increases, each year's contributions are added separately.

Example

  1. You start with $10,000 and invest $500 at the end of every month for 25 years, expecting a 7% average annual return and 2.5% inflation.
  2. The starting $10,000 grows to 10,000 × 1.07^25 = $54,274.33.
  3. The monthly rate is 1.07^(1/12) − 1 = 0.5654%, and 300 contributions of $500 grow to $391,520.94.
  4. Ending balance: $445,795.27, of which you contributed $160,000 and growth supplied $285,795.27.
  5. In today's dollars: 445,795.27 ÷ 1.025^25 = $240,457.77.
  6. If you also raise the monthly contribution by 3% each year, you contribute $228,755.59 and the balance reaches $570,169.78 ($307,544.21 in today's dollars).

Frequently asked questions

What return should I use?

Use an average annual return you think is realistic for your mix of investments, after fees, and then try a lower one as a stress test. There is no guaranteed rate for stocks or bonds, so treat any single projection as one scenario rather than a forecast.

What does "today's dollars" mean?

It is the future balance adjusted for inflation, so you can judge it against prices now. At 2.5% inflation, prices rise about 85% over 25 years, so $445,795 then buys roughly what $240,458 buys today.

What is a real return?

It is your return after inflation. A 7% return with 2.5% inflation is a real return of about 4.39% a year, calculated as 1.07 ÷ 1.025 − 1. Subtracting the two rates (4.5%) is a close but slightly high shortcut.

Should I invest monthly or once a year?

With the same yearly total, money invested monthly is in the market sooner on average, so it usually ends slightly ahead at the same return. Monthly investing also spreads purchases across different prices.

Does this include taxes?

No. Taxes depend on the account. Growth inside a 401(k) or traditional IRA is taxed when you withdraw it, qualified Roth withdrawals are tax-free, and in a regular brokerage account dividends and realized gains are taxed as you go.

Sources

Last reviewed for 2026. How we calculate.