Investment Calculator

Project the future value of an investment portfolio combining an initial sum and ongoing contributions.

How the Investment Calculator works

This calculator projects what a market portfolio could grow to using an expected return, not a guaranteed bank rate. It combines a one-time lump sum with recurring contributions and compounds both at the return you choose, treating the result as the midpoint of a wide range of possible outcomes rather than a promise.

The engine is the future-value-of-a-growing-account equation:

FV = P(1 + r/n)^nt + PMT × [((1 + r/n)^nt - 1) / (r/n)]

• FV = projected portfolio value at the end
• P = principal (your initial lump sum)
• r = expected annual return as a decimal (for example 0.07 for 7%)
• n = compounding periods per year (12 for monthly)
• t = time horizon in years
• PMT = the recurring contribution per period

The first term grows your lump sum; the second term is the annuity factor that grows every future contribution from the day it is invested.

What the tool does internally, step by step:

1. Converts your annual expected return to a periodic rate (r/n).
2. Converts your horizon to total periods (nt).
3. Compounds the lump sum forward with (1 + r/n)^nt.
4. Multiplies your per-period contribution by the annuity factor ((1 + r/n)^nt - 1)/(r/n).
5. Adds the two pieces, then splits the total into money you contributed versus market growth.

Edge cases it handles: If the expected return is 0%, the annuity term collapses to PMT × nt (a flat sum with no growth), avoiding division by zero. If PMT is 0, it behaves as a pure lump-sum projection. If P is 0, it projects contributions only. Because the return is an expectation, the tool's number is a central estimate, not a floor or a ceiling, and actual results will land somewhere around it depending on the real-world sequence of returns.

Example calculation

These three scenarios use realistic expected market returns, not bank rates, and every figure is recomputed from FV = P(1 + r/n)^nt + PMT × [((1 + r/n)^nt - 1)/(r/n)]. The 10% nominal and 7% real figures reflect the long-run U.S. large-cap average; your outcome is a midpoint, not a guarantee.

Scenario 1: Lump sum plus monthly, 8% expected, 20 years. You invest $25,000 today and add $500 a month for 20 years (n = 12, t = 20). The growth factor is (1 + 0.08/12)²⁴⁰ = 4.9268, so the lump sum becomes $25,000 × 4.9268 = $123,170. The annuity factor is (4.9268 - 1)/0.0066667 = 589.02, so contributions grow to $500 × 589.02 = $294,510. Total projected value is about $417,680 against $145,000 contributed, meaning roughly $272,680 is market growth.

Scenario 2: Contributions only, 10% nominal, 30 years. You start at $0 and invest $800 a month for 30 years at the 10% long-run nominal average. The annuity factor is ((1 + 0.10/12)³⁶⁰ - 1)/0.0083333 = 2,260.49, so the portfolio projects to $800 × 2,260.49 = about $1,808,390 on $288,000 contributed. Drop the assumption to a more conservative 6% (after fees and a softer market) and the same plan projects to only $803,612 - showing how sensitive the output is to the return you assume.

Scenario 3: Pure lump sum, 7% expected, 15 years. A $100,000 rollover invested with no further contributions grows to $100,000 × (1 + 0.07/12)¹⁸⁰ = about $284,895 with monthly compounding.

Scenario	Lump sum	Monthly	Return	Years	Contributed	Projected value	Growth
Lump + monthly	$25,000	$500	8%	20	$145,000	$417,680	$272,680
Contributions only	$0	$800	10%	30	$288,000	$1,808,390	$1,520,390
Lump only	$100,000	$0	7%	15	$100,000	$284,895	$184,895

One caution on Scenario 2: that $1.81M is in future dollars. Deflated at 3% inflation over 30 years, its real purchasing power is roughly $745,000 - which is why you should also model a real return on any portfolio you expect to hold this long.

Tips for using the Investment Calculator

• Run the projection twice: once at a nominal return (around 10% for U.S. large-cap) and once at a real return (around 7%, after subtracting roughly 3% inflation). The nominal number sets the contribution habit; the real number tells you what the balance actually buys.
• Subtract your fund's expense ratio from the expected return before you calculate. A 1% expense ratio cuts a 10% assumption to 9%, and on a $100,000 lump sum over 30 years (monthly compounding) that single percentage point erases roughly $510,000 of projected value - more than five times your starting balance.
• Treat the output as the middle of a fan, not a fixed endpoint. The same 7% average can produce very different real results depending on the order returns arrive in (sequence risk), so plan as if your actual outcome could be 20-30% above or below the midpoint.
• Model a bad-decade scenario by halving your expected return for the first 10 years, then restoring it. If your plan still reaches the goal, it is robust to a weak start; if it only works at a flawless 10%, it is fragile.
• Index your monthly contribution to inflation instead of leaving it flat. A static $500/month loses purchasing power every year; bumping it about 3% annually keeps your real savings rate constant and meaningfully lifts the ending balance.
• Use the lump-sum term and the contribution term separately to decide where new money helps most. Early in the horizon a lump sum dominates; late in the horizon contributions barely have time to compound, so front-load when you can.
• Hold the highest-return assumptions for tax-advantaged accounts. The same projection inside a Roth IRA or 401(k) keeps more of the growth, because a taxable brokerage loses a slice of dividends and gains to tax drag every year that this calculator does not subtract.
• When comparing a lump-sum investment today against dollar-cost averaging it in over a year, run both as separate projections rather than trusting intuition; lump-sum usually wins on the math because the money is exposed to growth sooner, but DCA lowers the regret if you invest right before a drop.
• Never plug a guaranteed bank APY into this tool and call it an investment plan. For an FDIC-insured account use the savings calculator instead - the expected-return engine here assumes a portfolio that can lose value in any given year.
• Re-run the projection every time you rebalance or change funds. Shifting from an 80/20 stock-bond mix toward 60/40 lowers your sensible expected return by roughly one to two points, which compounds into a very different number over 20-plus years.

Expected return vs guaranteed rate: why this calculator is different

The single most important thing to understand is that this tool uses an expected market return, while a savings calculator uses a guaranteed bank rate. That difference changes how you should read the output: a bank APY is a contract, but a market return is a long-run average that any individual year can wildly miss.

Over the long run, U.S. large-cap stocks have averaged roughly 10% nominal and about 7% after inflation, but individual years routinely swing from around -37% to +30% or more. A 4.5% high-yield savings account, by contrast, pays close to 4.5% every year and is insured up to FDIC limits. The arithmetic of compounding looks similar; the risk does not.

Feature	Investment calculator (this tool)	Savings calculator
Return type	Expected market average (not guaranteed)	Stated bank APY (contractual)
Typical input	7% real / 10% nominal	0.5% to 4.5% APY
Can lose value?	Yes, in any given year	No (insured deposit)
Output meaning	Midpoint of a wide range	Near-exact projection
Best for	Brokerage, IRA, 401(k), index funds	Emergency fund, short-term cash

Use the savings calculator for insured cash you cannot afford to lose, and this one for a long-horizon portfolio you can leave invested through downturns. If your money is going into a monthly mutual-fund plan rather than a lump-sum-plus-contributions mix, the SIP (monthly contribution) calculator frames the same math around recurring fund buys.

Nominal vs real return: the adjustment most projections skip

A nominal return ignores inflation; a real return subtracts it, and only the real return tells you what your future balance will actually buy. If your portfolio earns 10% nominal while inflation runs 3%, your real return is roughly 7%.

This matters enormously over long horizons. Scenario 2 above projects $1,808,390 at a 10% nominal return over 30 years, but deflated at 3% inflation its purchasing power is only about $745,000 in today's dollars. The balance is real; the spending power is less than half of what the headline number implies.

The practical fix is to run two projections. Use the nominal return (about 10% for U.S. stocks) when you are setting your monthly contribution, because that is the actual dollar figure that will appear on your statement. Use the real return (about 7%) when you are deciding whether the ending balance is enough to fund a goal priced in future dollars, like retirement spending or a home. To stress-test the inflation side directly, run the target through the inflation calculator before you trust any long-range total.

How to do it by hand or in Excel / Google Sheets

You can reproduce this calculator exactly with one spreadsheet function: =FV(rate, nper, pmt, pv). Excel and Google Sheets use the same syntax.

For Scenario 1 ($25,000 lump sum, $500/month, 8% expected, 20 years, monthly compounding), enter:

=FV(0.08/12, 240, -500, -25000)

This returns $417,680.28, matching the tool. Two rules matter: the rate must be periodic, so divide the annual return by 12 for monthly compounding (0.08/12), and contributions and the starting balance are entered as negative numbers because they are cash leaving your pocket. The 240 is nper (20 years × 12 months).

To find the contribution needed to hit a target instead, use =PMT(rate, nper, pv, fv). To discount a future goal to today's dollars, use =PV(rate, nper, pmt, fv).

By hand, work the formula in two halves: first compute the growth factor (1 + r/n)^nt, multiply it by your lump sum, then multiply your contribution by the annuity factor ((1 + r/n)^nt - 1)/(r/n), and add the two. If you only have a lump sum and no contributions, the simpler future value calculator covers it, and the compound interest calculator walks through the period-by-period compounding in detail.

Is this projection good? Benchmarks to sanity-check your number

A realistic expected return for a stock-heavy portfolio is about 7% real (10% nominal); anything you assume above 10% nominal is optimistic and anything below 5% is closer to a bond-heavy or cash mix. Use these reference points before you trust a projection.

• U.S. large-cap stocks: roughly 10% nominal / 7% real long-run average.
• 60/40 stock-bond portfolio: roughly 6% to 7% nominal expected, with lower volatility.
• Bonds alone: roughly 3% to 5% nominal in a normal rate environment.
• Cash / high-yield savings: roughly 0.5% to 4.5% APY - not an investment return.

A quick gut check is the Rule of 72: at a 7% real return money doubles about every 10.3 years, and at 10% nominal about every 7.2 years. If your projection shows money doubling faster than that, your assumed return is too high for any diversified portfolio. As a contribution benchmark, saving 15% of gross income (including any employer match) is the widely cited target for a comfortable retirement; the retirement calculator ties that rate to a specific goal.

Common mistakes that wreck investment projections

The most expensive mistake is assuming a return that is too high, because the error compounds for decades. Plugging in 12% instead of a realistic 7% real can roughly double your projected balance and leave you under-saving for years before you notice.

The second mistake is forgetting fees. This calculator does not subtract your fund's expense ratio automatically. A 1% expense ratio quietly turns a 10% return into 9%, and over 30 years on a $100,000 lump sum (monthly compounding) that gap costs about $510,000 in lost value. Always enter the return net of fees.

The third mistake is treating the midpoint as a guarantee. Markets do not deliver 7% in a smooth line; they deliver it as a jagged average with deep drawdowns. A string of bad early years (sequence risk) can leave you well below the projection even if the long-run average eventually holds.

The fourth mistake is ignoring taxes in a brokerage account. Dividends and realized gains are taxed yearly outside retirement accounts, dragging down the real growth this tool shows. The fifth is comparing apples to oranges - dropping a guaranteed bank APY into the return field. For insured cash, the savings calculator is the right tool; for a guaranteed-rate CD, model it as a fixed rate, not a market return.

Sequence-of-returns and volatility risk: why the midpoint hides danger

Two portfolios with the identical average return can end at very different places depending on the order the returns arrive - that is sequence risk, and this calculator's smooth midpoint cannot show it.

While you are contributing and not withdrawing, a rough early market is actually helpful, because your contributions buy more shares cheaply before the recovery. The danger flips near and during retirement: a crash in your first few withdrawal years, combined with selling assets to live on, can permanently shrink the portfolio even if the long-run average is fine. That is why two retirees who both average 7% can have opposite outcomes.

The practical takeaway is to treat the projection as a planning center, not a destiny. Build in a margin of safety: aim to overshoot the target, hold one to two years of spending in cash as you approach the goal, and re-run the numbers in a downturn rather than abandoning the plan. When you reach the drawdown phase, model your spending with the retirement withdrawal calculator rather than this accumulation tool, which assumes no withdrawals.

Advanced uses and account-specific notes

The same engine handles several planning jobs beyond a single brokerage projection - the trick is changing what P, PMT, and r represent.

Maxing tax-advantaged accounts: Set PMT to the monthly equivalent of the contribution limit and use a real return to see the after-inflation balance. For a 401(k), include the employer match in PMT, and pair the result with the 401(k) calculator to handle the match cap precisely.

Roth vs taxable: Run the projection once for a Roth IRA (no tax on growth, so the full balance is yours) and once for a taxable account using a slightly lower net return to approximate annual tax drag on dividends.

FIRE planning: Use this tool for the accumulation half - the years you are adding contributions - then hand the ending balance to the FIRE calculator to test whether it sustains your target spending. To see when a specific contribution rate crosses seven figures, the millionaire calculator answers that directly.

Comparing one investment to another: If you want the simple percentage gain on a single buy-and-sell rather than a multi-year contribution plan, the ROI calculator is the cleaner fit. This tool is built for the steady, contribute-and-compound portfolio, which is where most long-term wealth is actually built.

Investment growth quick reference: how lump sums and monthly contributions project at 5%, 7%, and 10%

Here is a fast lookup for how money grows at three common expected returns: 5% (conservative or balanced), 7% (the long-run S&P 500 real, after-inflation average), and 10% (the long-run nominal average before inflation). Every figure below is recomputed with standard compounding (lump sums compounded annually, monthly contributions compounded monthly) and is an expected midpoint of a wide range, not a guarantee. Fees, taxes, and the order of good and bad years will all move your real result.

Scenario	You invest	5% return	7% return	10% return
$10,000 lump, 10 years	$10,000	$16,289	$19,672	$25,937
$10,000 lump, 20 years	$10,000	$26,533	$38,697	$67,275
$10,000 lump, 30 years	$10,000	$43,219	$76,123	$174,494
$500/month, 10 years	$60,000	$77,641	$86,542	$102,422
$500/month, 20 years	$120,000	$205,517	$260,463	$379,684
$500/month, 30 years	$180,000	$416,129	$609,985	$1,130,244

Notice the spread: the same $500 a month for 30 years lands anywhere from about $416,129 to $1,130,244 depending only on the return rate. That gap is why the investment calculator output is a planning midpoint, and why a 1% expense ratio or a stretch of weak years matters so much over long horizons.

Related on this site

compound interest calculator · SIP (monthly contribution) calculator · retirement calculator · Roth IRA calculator · millionaire calculator · inflation calculator

For a related deep dive, see SEC Investor.gov compound interest.

Investment Calculator — frequently asked questions

Are returns guaranteed?

No — markets fluctuate. Use a conservative return and remember past performance is not a promise.

Before or after inflation?

For purchasing power, use a real return (e.g. 4–5%) instead of nominal 8%.

Are returns guaranteed?

No — markets fluctuate and past performance doesn't predict the future.

Nominal or real return?

For purchasing power, use a real return (around 4–5%) instead of nominal.

How much does a $10,000 investment grow to in 30 years at a 7% real return?

About $76,123 at a 7% real (after-inflation) annual return, in today's dollars. The math: $10,000 x 1.07³⁰ = $76,123 with no extra contributions. At a 10% nominal return it would show roughly $174,494, but that bigger number buys about the same as $76,123 because inflation erodes it. The <a href="/investment-calculator/">investment calculator</a> projects an expected midpoint, not a guarantee.

How much does investing $500 a month for 25 years earn at 8%?

Investing $500 a month for 25 years at an 8% expected return projects to about $475,513, of which only $150,000 is your own money. That means roughly $325,513 is growth from compounding. This assumes monthly compounding and a steady 8% nominal return every year, which never happens in reality, so treat it as the center of a wide range. Compare with the <a href="/sip-calculator/">SIP calculator</a> for a mutual-fund framing.

What is the difference between this and the savings calculator?

This investment calculator projects an EXPECTED, not guaranteed, market return (commonly 7% real or 10% nominal for a stock-heavy portfolio), so results swing widely year to year. The <a href="/savings-calculator/">savings calculator</a> models an insured bank account at a known, far lower rate (often 0.5-4.5% APY) with no risk of loss. Use savings for an emergency fund; use this tool for long-horizon investing where volatility is acceptable.

How do I project investment growth in Excel?

Use Excel's FV function: =FV(rate/12, years*12, -monthly, -lump). For $25,000 plus $500/month at 8% over 20 years, enter =FV(0.08/12, 240, -500, -25000), which returns about $417,680. Make contributions and the lump sum negative (cash out) so the result is positive. To project a real return, replace 0.08 with your after-inflation rate, such as 0.05. This matches the <a href="/investment-calculator/">calculator</a>.

How much does a 1% expense ratio cost over 30 years on $100,000?

About $176,277 on a $100,000 lump sum over 30 years, comparing a 1% fund with a near-zero 0.05% fund (annual compounding). At a 7% gross return, the 0.05% fund nets roughly 6.95% and grows to about $750,626, while the 1% fund nets 6% and grows to only $574,349. That fee gap quietly takes nearly a quarter of your potential balance, which is why low-cost index funds matter so much.

Is a 10% return realistic for the stock market?

A 10% nominal return is the rough long-run historical average of the S&P 500, but it is not realistic for any single year. After inflation, the real average is closer to 7%. Individual years routinely range from about -37% to +30% or more, so the 10% figure only describes a multi-decade average. For purchasing-power planning, use 7% real; the 10% number ignores inflation entirely.

How much do I need to invest monthly to reach $1 million in 30 years?

About $671 a month at an 8% expected return reaches $1 million in 30 years, with no starting lump sum. The math uses the future-value-of-an-annuity formula and monthly compounding. At a more conservative 7%, you would need about $820 a month. Both assume steady returns that real markets do not deliver smoothly, so build in a buffer. See the <a href="/millionaire-calculator/">millionaire calculator</a>.

What is sequence-of-returns risk and does this calculator show it?

Sequence-of-returns risk is the danger that poor returns early on, or right before and after you start withdrawing, hurt your balance far more than the same returns spread out differently. No, this calculator does not model it: it applies one smooth average rate, so it ignores the order of good and bad years. The risk matters most near retirement. The <a href="/retirement-withdrawal-calculator/">retirement withdrawal calculator</a> helps with drawdown planning.

How much does $200 a month grow to in 40 years at 7%?

Investing $200 a month for 40 years at a 7% return projects to about $524,963, while you only contribute $96,000 of your own money. Roughly $428,963 comes from compounding, which shows why starting young beats investing more later. This assumes monthly compounding and a steady 7% return; actual results will swing above and below this midpoint over four decades.

Should I use nominal or real return for retirement planning?

Use a real (after-inflation) return, around 7% for stocks, when you want results in today's purchasing power. Nominal returns near 10% produce bigger headline numbers but those future dollars buy less. For example, $20,000 over 30 years shows about $348,988 at 10% nominal versus $152,245 at 7% real, yet they represent similar real wealth. Pick one approach and stay consistent across the <a href="/retirement-calculator/">retirement calculator</a> too.

Is lump-sum investing better than dollar-cost averaging?

Historically, investing a lump sum immediately beats spreading it out about two-thirds of the time, because markets rise more often than they fall, so money invested sooner compounds longer. A $60,000 lump sum at 8% over 30 years projects to about $603,759 (annual compounding). Dollar-cost averaging trades some expected return for lower regret and timing risk. This calculator assumes your lump sum is invested on day one.

How wide is the range around the projected investment value?

Very wide: the single number this tool shows is the midpoint of outcomes that can differ by hundreds of thousands of dollars. For $500 a month over 30 years, a 5% return projects about $416,129, 8% projects about $745,180, and 9% projects about $915,372, all from the same $180,000 invested. Real returns vary year to year, so treat the output as a planning estimate, never a promise.

How much does a $50,000 lump sum earn in 20 years at 6%?

A $50,000 lump sum at a 6% annual return projects to about $160,357 in 20 years (annual compounding), with roughly $110,357 in growth and no additional contributions. The formula is $50,000 x 1.06²⁰. A 6% rate is a reasonable estimate for a balanced stock-and-bond portfolio; a stock-heavy mix might target 7% real, while bonds alone would be lower. Returns are expected, not guaranteed.

Does the calculator account for taxes on investment gains?

No, this calculator shows pre-tax growth and ignores capital-gains and dividend taxes, which can take 15-20% or more of gains in a taxable account. To approximate after-tax results, shave roughly 0.5-1% off your return rate in a taxable brokerage. Tax-advantaged accounts like a <a href="/roth-ira-calculator/">Roth IRA</a> or <a href="/401k-calculator/">401(k)</a> let gains compound tax-free or tax-deferred, so the gross projection is more accurate there.

Is investing $1,000 a month for 10 years worth it?

Yes, especially as a foundation: $1,000 a month for 10 years at 8% projects to about $182,946, with $120,000 from you and roughly $62,946 from growth. Ten years is a short horizon for stocks, so a market downturn near the end could leave you below this midpoint. Whether it is worth it depends on your goals and risk tolerance; longer horizons let compounding do far more of the work.

How many years until my investment doubles?

Use the Rule of 72: divide 72 by your expected return to estimate doubling time. At 8% your money roughly doubles every 9 years (72 / 8), at 10% every 7.2 years, and at a 7% real return every 10.3 years. So $10,000 at 8% becomes about $20,000 in 9 years and $40,000 in 18 years. The <a href="/rule-of-72-calculator/">Rule of 72 calculator</a> shows this instantly; it is an estimate, not exact.

Guides & articles

• What Rate of Return Should You Use in an Investment Calculator?
• Why Your Investment Projection Is Wrong - and How to Make It Honest

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