Investment Calculator
A lump sum, regular contributions, and what the pot is worth in today’s money
Year by year projection, nominal and inflation adjusted
| Year | Paid in | Growth | End balance | Today’s money |
|---|
What the projection says
The headline figure counts dollars. It is the number every other investment calculator stops at, and it is the number a statement will show you in twenty five years.
What the projection buys
The real figure counts groceries, rent and fuel. It is the same pot measured against what a dollar will be worth by then, which is the only version you can spend.
The real return is (1 + nominal) ÷ (1 + inflation) − 1, not nominal minus inflation. At 7 percent against 3 percent that is 3.8835 percent a year rather than 4 percent, and on a $20,000 lump sum over 25 years the shortcut overstates the answer by $1,474.
What return should go in the box?
Every figure below is an annual average with its source and the date it was read. Averages are what a long run produced, not what any single year will produce.
| Asset | Average a year | Read |
|---|---|---|
| S&P 500, nominal, 1957 to Aug 2026 | 10.69% | 2026-09-23 |
| S&P 500, after inflation, same window | 6.82% | 2026-09-23 |
| Commonly suggested planning rate | 6% to 7% | 2026-09-23 |
| Bonds, long run range | 3% to 5% | 2026-09-23 |
| Bond funds, mid 2026 | upwards of 4% | 2026-09-23 |
| High yield savings | 3% to 4% | 2026-09-23 |
| US house prices, 1992 to 2024 | 5.4% | 2026-09-23 |
| US inflation, 12 months to Aug 2026 | 3.4% | 2026-09-23 |
| Federal Reserve inflation target | 2% | 2026-09-23 |
Costs come straight off the top of whichever rate you pick. These are the 2025 asset weighted industry averages.
| Fund type | Average cost a year | On $100k over 30 years |
|---|---|---|
| Index bond ETFs | 0.09% | Keeps most of it |
| Index equity ETFs | 0.14% | $729,895 |
| Bond mutual funds | 0.36% | Middle |
| Equity mutual funds | 0.40% | $674,984 |
| A one percent annual charge | 1.00% | $563,079 |
Where the money can actually go
The projection is the same in every wrapper. The tax is not, and the tax is often worth more than the difference between a 6 and a 7 percent return assumption. 2026 figures.
| Account | 2026 limit | Tax on the growth |
|---|---|---|
| Taxable brokerage | No limit | Capital gains |
| Traditional IRA | $7,500 | Deferred |
| Roth IRA | $7,500 | None on qualified withdrawals |
| IRA catch up, age 50 and over | plus $1,100 | Same as the IRA |
| Roth IRA phase out, single | $153,000 to $168,000 | Eligibility tapers |
| Roth IRA phase out, joint | $242,000 to $252,000 | Eligibility tapers |
If the money sits in a taxable account, the rate depends on how long you held the asset and what else you earned that year.
| Gain | Rate | 2026 threshold |
|---|---|---|
| Held a year or less | 10% to 37% | Ordinary income |
| Held more than a year | 0% | to $49,450 single, $98,900 joint |
| Held more than a year | 15% | to $545,500 single, $613,700 joint |
| Held more than a year | 20% | above those figures |
| Net investment income tax | plus 3.8% | High earners |
The number, and what the number will buy
Why the contributions matter more than the lump sum, why the real return is never nominal minus inflation, what fees quietly remove, and why the order of the good years is not the detail you think it is.
Every investment projection answers the same question twice. Once in dollars, which is what a statement will say, and once in buying power, which is the only version you can actually spend. This investment calculator prints both, side by side, for every year of the horizon. Put in what you already have, what you can add each month, how long the money has, and a rate of return, and the table below the inputs gives you the end balance and the same balance measured in today's money, year on year, so you can watch the gap between the two open up.
The arithmetic is a lump sum and a stream of deposits added together: FV = PV(1 + i)ⁿ + PMT × ((1 + i)ⁿ − 1) / i, with one extra multiplication by (1 + i) if the deposits land at the start of each period rather than the end. That is the whole formula, stated once. If you want it taken apart, the compound interest calculator owns that job and covers compounding frequency properly. This page is about the investing decisions wrapped around it.
The worked example, start to finish
Take $20,000 already invested, $500 added at the end of every month, 25 years, and 7 percent a year. The projection ends at $500,070. You put in $170,000 of that, the $20,000 opening balance plus $150,000 of contributions, so $330,070 is growth, which is 66.0 percent of the final pot. Set inflation to 3 percent and the same pot is worth $238,836 in today's money. Nothing has gone wrong. Both figures are correct, and they describe the same money.
The contributions do most of the work
Run that example again with the contributions switched off and the $20,000 grows to $108,549 on its own. So of the $500,070 total, $391,521 exists because of the $500 a month. That is 78 percent of the outcome coming from the part of the plan you control every month, and it reframes the whole exercise: people spend a long time agonising over the return assumption, which they cannot control, and very little time on the contribution, which they can. Raising $500 to $600 lifts the ending balance to $578,374, a gain of 15.7 percent, and it is a change you can make this month. Moving the return assumption from 7 to 8 percent lifts it to $591,465, a slightly larger gain, but nobody gets to decide that one.
There is a smaller lever beside it. Contributions can be set to land at the start of each period instead of the end, which buys every deposit one extra period of growth. On the worked example that is worth about $2,214, a rounding error next to the contribution itself, but free if your payday allows it.
Real against nominal, and the mistake almost everyone makes
Here is the part that most investment calculators get wrong, including two of the fifteen highest ranking pages for this search. The real rate of return is not the nominal rate minus inflation. It is the Fisher relation:
real = (1 + nominal) / (1 + inflation) − 1
At 7 percent against 3 percent inflation that gives 3.8835 percent a year, not 4 percent. The gap looks trivial and is not, because it compounds. A $20,000 lump sum over 25 years is worth $51,843 in today's money, but the subtraction shortcut says $53,317, overstating the answer by $1,474 or 2.84 percent. Stretch it to 40 years and the shortcut claims $96,020 against a true $91,810, an error of 4.59 percent. The error gets worse as inflation rises, which is exactly when a reader most needs the honest number: at 10 percent nominal against 8 percent inflation the real return is 1.85 percent, and subtraction would have told you 2 percent, a claim that is eight percent too generous about the only part of the return that matters.
The last column of the table applies this properly, dividing each year's balance by (1 + inflation) raised to that year's power. Watch what it does over a long horizon. Most of the impressive growth in the final decade of a thirty year projection is inflation rather than wealth, and seeing the two columns drift apart row by row makes that clear in a way a single end figure never does.
What the fund charges, before anything else happens
An annual charge comes off the top, every year, whether the market went up or down. The regulator's own illustration makes the point with a $100,000 portfolio returning 4 percent over 20 years: at a 0.25 percent annual fee it ends near $208,000, at 0.50 percent near $198,000, and at 1 percent near $179,000. A quarter of a percent against one percent is roughly $29,000 of the same person's money.
Push it further with the cost box on this page. $100,000 at 7 percent for 30 years reaches $761,226 untouched. A one percent annual charge leaves $563,079, so the charge took $198,147, which is 26.0 percent of the pot. Nobody agrees to hand over a quarter of their retirement, yet one percent sounds small enough to sign. The 2025 industry averages are 0.40 percent for equity mutual funds, 0.36 percent for bond mutual funds, 0.14 percent for index equity ETFs and 0.09 percent for index bond ETFs. On that same $100,000 over 30 years, the difference between the 0.14 percent average and the 0.40 percent average is $54,911.
Does the order of the good years matter?
For a lump sum sitting still, no, and this is worth knowing because it is repeated wrongly so often. Multiplication does not care about order, so $100,000 run through ten given annual returns ends at exactly the same balance whichever way round they arrive. Run the returns -20, -10, 5, 10, 15, 20, 25, 30, -5 and 12 percent in that order or in reverse and the answer is $198,421 either way.
Once you are contributing, the order matters enormously, and it runs the opposite way to the retirement warnings you may have read. Invest $10,000 at the end of each of those same ten years and the sequence above, with the two bad years first, ends at $186,178. The exact same ten returns in reverse, with the good years first, end at $112,825. Same average, same set, a 65 percent difference in outcome, and the version with the crash at the beginning is the one that wins, because every contribution during the bad years bought in cheap and then rode the recovery. A falling market while you are still buying is not the disaster it feels like. That is a fact about accumulation specifically, not a general law, and it reverses once you start withdrawing.
A fixed contribution is a shrinking contribution
The contribution box is the one input everybody fills in once and then leaves alone for thirty years. In real terms $500 a month in year 30 is worth about $206 at 3 percent inflation. If the plan is to keep the same pressure on the goal, the contribution has to rise with prices, which is what the escalation input is for. Setting it to 3 percent on the worked example adds roughly $124,000 to the ending balance, and it costs nothing you would notice in any single year.
Where the money actually sits
The projection is identical in every wrapper. The tax is not, and it is often worth more than the argument between a 6 and a 7 percent return assumption. A taxable brokerage account has no limit but the gains are taxable: held a year or less they are ordinary income at 10 to 37 percent, held longer they fall into the 0, 15 and 20 percent long term bands, with 0 percent running to $49,450 of taxable income for a single filer and $98,900 filing jointly in 2026, and a further 3.8 percent net investment income tax for high earners. A traditional IRA defers the tax and a Roth IRA removes it on qualified withdrawals, both capped at $7,500 in 2026 with $1,100 more from age 50. Roth eligibility tapers between $153,000 and $168,000 single, $242,000 and $252,000 joint. Workplace plans have their own rules and their own arithmetic, which the 401k calculator handles.
What this projection is not
It is a straight line drawn through something that has never moved in a straight line. No real portfolio returns 7 percent every year; it returns 22 percent, then minus 9, then 14, and averages out to something in the end. The value of a projection is not the precision of the final figure, which will be wrong. It is the comparison: this contribution against that one, this cost against that one, this horizon against a shorter one. Change one input, watch the two columns move, and use the size of the move rather than the number itself.
Frequently Asked Questions
What is the difference between a nominal and a real investment return?
The nominal return counts dollars. The real return counts what those dollars buy. If a portfolio grows 7 percent in a year while prices rise 3 percent, you have 7 percent more money and roughly 3.9 percent more buying power. Over a long horizon the two answers separate dramatically: $20,000 at 7 percent for 25 years is $108,549 nominal and $51,843 in today's money. Both are correct and they describe the same pot, which is why the table on this page carries a column for each.
Why is the real return not just the return minus inflation?
Because returns and inflation both compound, so they divide rather than subtract. The exact relation is real = (1 + nominal) / (1 + inflation) - 1. At 7 percent against 3 percent that is 3.8835 percent a year, not the 4 percent that subtraction suggests. On a $20,000 lump sum over 25 years the shortcut overstates the answer by $1,474, and over 40 years by 4.59 percent. The error grows with inflation, so it is largest exactly when the honest figure matters most.
How much of my final balance comes from contributions rather than the starting amount?
Usually far more than people expect. In the worked example, $20,000 plus $500 a month for 25 years at 7 percent reaches $500,070. The opening $20,000 on its own would have reached $108,549, so $391,521 of the total, about 78 percent, exists because of the monthly contributions. The results panel splits the two out for whatever numbers you enter, which is useful because the contribution is the part of the plan you can actually change.
What does a one percent annual fund charge actually cost me?
About a quarter of the pot over a working lifetime. $100,000 at 7 percent for 30 years reaches $761,226 with no charges and $563,079 with a 1 percent annual charge, so the charge took $198,147, or 26.0 percent. The 2025 industry averages are 0.40 percent for equity mutual funds and 0.14 percent for index equity ETFs, and on that same $100,000 over 30 years the gap between those two averages alone is $54,911. Put your fund's figure in the annual cost box and the projection is recalculated net of it.
Does the order of good and bad years change my final balance?
Not for a lump sum left alone, because multiplication ignores order. Ten given annual returns applied to $100,000 end at $198,421 whichever way round they arrive. Once you are contributing it matters a great deal. Investing $10,000 at the end of each of those ten years ends at $186,178 with the two bad years first and $112,825 with the good years first, from the same set of returns. A falling market while you are still buying works in your favour, which is the opposite of how sequence risk behaves once you are withdrawing.
Why does a fixed monthly contribution lose ground over time?
Because the amount stays the same while prices do not. At 3 percent inflation, $500 a month in thirty years time has about $206 of today's buying power, so the plan quietly weakens every year even though the number in the box never changes. The escalation input fixes it: raise the contribution by roughly the inflation rate and its real weight stays level. On the worked example, escalating at 3 percent a year adds around $124,000 to the ending balance.
What happens to the projection if I stop contributing halfway through?
The balance keeps compounding but stops being fed, so the curve flattens noticeably. Project the full horizon, note the balance at the year you would stop, then run a second projection using that balance as the starting amount, zero contributions and the remaining years. The difference between the two end figures is what the abandoned contributions would have been worth, and because the later contributions have the least time to grow, stopping early costs less than starting late does.
Should the money sit in a brokerage account or an IRA?
The growth is identical, the tax is not. A taxable brokerage account has no contribution limit, but gains held more than a year are taxed at 0, 15 or 20 percent depending on income, gains held a year or less are taxed as ordinary income at 10 to 37 percent, and high earners add a 3.8 percent net investment income tax. A traditional IRA defers tax on the growth and a Roth IRA removes it on qualified withdrawals, both capped at $7,500 in 2026 with an extra $1,100 from age 50. In practice the limits decide it: fill the tax advantaged space first, then use the brokerage account for anything above it.
Is the S&P 500 long run average a safe number to project with?
It is a reasonable anchor and a poor promise. From the start of 1957 to August 2026 the index averaged 10.69 percent a year with dividends reinvested, which falls to 6.82 percent once inflation is taken out. That is why most planning guidance suggests projecting with 6 or 7 percent rather than 10: the lower figure is roughly the real one, and using it with the inflation field at zero gives you a today's money answer without the second column. A single portfolio also holds bonds and cash, which have averaged 3 to 5 percent, so a mixed portfolio should assume less than the index alone.