CalcLibrary

DCA Investment Calculator

See what consistent monthly investing builds over time. Enter what you can put aside each month, how long you'll keep it up, and your expected return — get the future value, what you actually paid in, and how much of the result is pure compound growth.

Examples

Classic 30-year — $500/month at 7%

Example retirement scenario: $500 every month for 30 years at a 7% return.

Monthly Contribution
$500
Years Invested
30 years
Expected Annual Return
7 %
Starting Balance
$0
Final Value
$609,985
Total Contributed
$180,000
Total Gain
$429,985

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How It Works

Formula

FV=P⋅(1+r)n−1r+PV⋅(1+r)nFV = P \cdot \frac{(1 + r)^n - 1}{r} + PV \cdot (1 + r)^n

Variables, symbols and units

FVFV

Final value at the end of the period

PP

Monthly contribution

PVPV

Starting balance (lump sum already invested)

rr

Monthly return rate (annual return ÷ 12, as a decimal)

nn

Total months invested (years × 12)
Calculation method explained

Applies an ordinary-annuity future-value formula to equal monthly contributions at a constant monthly return, then adds the compounded future value of any starting balance.

References and source material

Examples

Classic 30-year — $500/month at 7%$500 · 30 years → $609,985

Example retirement scenario: $500 every month for 30 years at a 7% return.

Monthly Contribution
$500
Years Invested
30 years
Expected Annual Return
7 %
Starting Balance
$0
Final Value
$609,985
Long-horizon DCA — $500/month for 20 years at 7%$500 · 20 years → $260,463

Steady monthly contributions over a long horizon — modest amounts compounding through 20 years.

Monthly Contribution
$500
Years Invested
20 years
Expected Annual Return
7 %
Starting Balance
$0
Final Value
$260,463
Boosting an existing portfolio — €800/month + €20,000 start$800 · 15 years → $281,737

Already have €20,000 invested? See what €800/month at 6% looks like over 15 years.

Monthly Contribution
$800
Years Invested
15 years
Expected Annual Return
6 %
Starting Balance
$20,000
Final Value
$281,737

Frequently Asked Questions

How is this different from a compound interest calculator?
A compound interest calculator usually focuses on a single lump sum compounding forward. DCA flips the focus to the monthly contribution as the engine — you keep dripping money in over decades, every dollar gets a slightly shorter compounding window than the one before it, and the total grows from contributions plus compound growth on each. Use a compound interest calculator when you have a lump sum sitting still; use this when you're investing on a schedule.
What return rate should I use — 7%, 10%, or 12%?
Use a rate that matches the scenario you want to test. This calculator applies the same estimated annual return every month for the whole period, so it is a planning model rather than a forecast.
Does this account for inflation, fees, or taxes?
No — the result is a gross, nominal projection. To approximate a real (inflation-adjusted) result, plug in your expected return minus expected inflation. Fees reduce your effective return; subtract them from the rate if you want to model them. Taxes depend on account type and local rules, so this calculator does not model tax treatment or contribution limits.
What happens if I miss a month or two of contributions?
Missing contributions lowers the result because less money goes in and those dollars have less time to compound. This calculator assumes the same contribution is made every month, so skipped months are not modeled separately.
Should I use a conservative return rate?
A lower estimated return gives you a more conservative projection. Try a few rates to see how sensitive the result is to this assumption.

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