Calculateus

Investment Calculator

Project the growth of a lump-sum and recurring investment over time.

Result

Future Value
$103,044.16
Total Invested
$50,000.00
Total Growth
$53,044.16
Portfolio ValueInvested
$200K$150K$100K$50K$0Portfolio Value - Yr 1: $9KPortfolio Value - Yr 2: $12KPortfolio Value - Yr 3: $16KPortfolio Value - Yr 4: $21KPortfolio Value - Yr 5: $26KPortfolio Value - Yr 6: $31KPortfolio Value - Yr 7: $37KPortfolio Value - Yr 8: $43KPortfolio Value - Yr 9: $50KPortfolio Value - Yr 10: $57KPortfolio Value - Yr 11: $65KPortfolio Value - Yr 12: $73KPortfolio Value - Yr 13: $82KPortfolio Value - Yr 14: $92KPortfolio Value - Yr 15: $103KInvested - Yr 1: $8KInvested - Yr 2: $11KInvested - Yr 3: $14KInvested - Yr 4: $17KInvested - Yr 5: $20KInvested - Yr 6: $23KInvested - Yr 7: $26KInvested - Yr 8: $29KInvested - Yr 9: $32KInvested - Yr 10: $35KInvested - Yr 11: $38KInvested - Yr 12: $41KInvested - Yr 13: $44KInvested - Yr 14: $47KInvested - Yr 15: $50KYr 1Yr 3Yr 5Yr 7Yr 9Yr 11Yr 13Yr 15

About the Investment Calculator

Whether you're investing a lump sum, contributing monthly, or both, the question is always the same: what will this actually be worth years from now? Our Investment Calculator projects the future value of your investment based on your starting amount, monthly additions, expected return, and time horizon.

How It Works

The calculator compounds your initial investment monthly at your chosen rate of return, adding your monthly contribution at the end of each period. Over your selected time horizon, it totals up your contributions separately from the growth so you can see exactly how much of the final balance came from your own money versus investment returns.

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

Formula & Methodology

This is the identical future-value-with-contributions formula used across all of this site's growth projections - a lump sum compounding on its own, plus a stream of contributions each compounding for the remaining time after it's deposited. Separating 'your contributions' from 'growth' in the output matters because it's the clearest way to see how much of a long-term projection is really coming from the market versus from your own savings discipline.

Step-by-Step: Calculating It By Hand

  1. 1Convert your annual expected return to a monthly rate.
  2. 2Convert your investment horizon to total months.
  3. 3Compound the initial lump sum using P(1+r)^n.
  4. 4Add the compounded value of monthly contributions using the annuity formula, then total the two.

Examples

Lump sum plus contributions

$5,000 invested today plus $250/month at 8% for 15 years grows to roughly $92,000, with about $47,000 of that from growth alone.

Lump sum only

The same $5,000 with no further contributions, at the same rate and time, grows to a much smaller figure - showing how much regular contributions matter.

Advantages

  • Separates your contributions from your actual investment growth
  • Works for any combination of lump-sum and recurring contributions
  • Helps you set realistic expectations for a chosen time horizon
  • Quick to test 'what if I invested $50 more per month' scenarios

Common Mistakes

  • Using an overly optimistic rate of return not grounded in historical averages
  • Forgetting that returns are never perfectly smooth year to year
  • Not accounting for fees, which can meaningfully reduce real returns over time
  • Ignoring taxes on gains in a taxable brokerage account

Edge Cases to Watch For

  • A higher assumed rate of return dramatically changes long-horizon projections - small differences in the assumed rate compound into large differences in the final figure over 20-30 years.
  • This models a constant contribution amount; a contribution that grows with income (common in practice) would produce a higher actual balance than this static projection.
  • Investment fees (expense ratios, advisory fees) reduce your effective rate of return below the market's headline return.
  • This is a nominal (non-inflation-adjusted) projection - the real purchasing power of the final figure will be lower after accounting for inflation.

Common Use Cases

  • Projecting growth of a brokerage account or investment fund
  • Comparing different monthly contribution amounts
  • Estimating progress toward a specific savings goal
  • Understanding the long-term impact of starting to invest sooner
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

What return rate should I assume?

Historically the S&P 500 has averaged around 7-10% annually before inflation over long periods, though any single year can vary widely - using a conservative estimate (6-8%) is safer for planning than assuming best-case returns.

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Conclusion

Small, consistent investments compounded over time can add up to far more than most people expect. Use this calculator to model your own numbers realistically, and revisit it whenever your contribution amount or goals change.

References