Calculation details
Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.
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What does this calculator estimate?
Investing $500/month for 10 years at a 7 percent annual return grows to about $87,000 with only $60,000 contributed. Monthly return = annual return / 12.
- DCA grows each month as (current value + contribution) x (1 + monthly return) (Wikipedia).
- Monthly return = annual return / 12.
- Dollar-cost averaging lowers the timing risk of lump-sum investing.
How dollar-cost averaging works
DCA invests a fixed amount on a regular schedule — buying more shares when prices are low, fewer when high. It removes timing decisions and smooths volatility. The calculator projects the compounding result of consistent contributions.
Limitations to watch for
The projection assumes a constant return — markets fluctuate year to year, so the actual range is wide. DCA doesn't guarantee returns and can underperform a lump sum in steadily rising markets (you bought fewer shares early). It's a discipline, not an optimization.
How to use it in practice
Set an affordable monthly contribution and automate it. Use a conservative long-term return assumption (4–7% real for broad index funds). Increase contributions as income grows.
['Enter the monthly contribution.', 'Enter an expected annual return and the years.', 'Read the projected value and total contributed.']
The mechanics of dollar-cost averaging
DCA invests a fixed amount on a schedule — $500 monthly, for example — buying more shares when prices are low and fewer when high. The average cost per share smooths volatility without trying to time the market. The calculator projects the portfolio value from the monthly contribution, expected return, and horizon.
The lump-sum comparison
Historical data shows lump-sum investing outperforms DCA roughly two-thirds of the time because markets trend upward. But that is an average: if a sudden drop would make you sell in panic, spreading the entry may keep you invested — which beats the average outcome abandoned. The calculator shows both paths side by side at the same return.
Contributions vs. returns over time
Early in a DCA plan, your own contributions dominate the balance; later, growth takes over. A $500 monthly plan at 7 percent for 10 years ends near $86,000, of which $60,000 is contributions and $26,000 is growth. At 30 years, the balance approaches $610,000 with only $180,000 contributed — the compounding curve is why starting early matters.
Sequence risk is the real enemy
The worst outcome for a saver is not a bad entry price; it is stopping contributions or selling during a downturn. DCA turns volatility into a disciplined buying process. The calculator models constant returns; the discipline is what makes the plan work through the years the market does not cooperate.
A worked example
$12,000 invested as a lump sum at 7 percent for 10 years grows to about $23,600. The same $12,000 contributed at $1,000 monthly over 12 months, then left to grow, reaches about $23,100 — a small gap, because the uninvested cash also earns along the way. The calculator shows both trajectories so the trade-off is concrete.
How this calculator works
Formula
Simulates monthly contributions compounding: each month, new value = (current value + contribution) × (1 + monthly return). Monthly return = annual return ÷ 12.
Worked example
Investing $500/month for 10 years at 7% annual return grows to about $87,000 — with only $60,000 contributed.
Assumptions to verify
- Contributions are made monthly at the entered amount.
- Returns compound monthly at the constant annual rate.
- No withdrawals are made.
Frequently asked questions
What is dollar-cost averaging?
Investing a fixed amount on a regular schedule regardless of price — buying more when cheap, less when expensive.
How much does $500/month become?
At 7% over 10 years, about $87,000 from $60,000 contributed — the rest is compounding.
Why is DCA better than lump sum?
It removes timing risk and emotion. Historically, lump sum often outperforms, but DCA is easier to sustain and psychologically safer.
What return should I assume?
Conservative planning uses 4–7% for broad index funds. Past performance isn't a guarantee.
Does it work in down markets?
Yes — that's the point: lower prices buy more shares, which pays off when the market recovers.
How do I start?
Automate a monthly transfer to an index fund or ETF and increase it with raises.
Is this financial advice?
No — the calculator projects math under your assumptions. Decisions are yours.
How does dollar-cost averaging work?
Invest a fixed amount on a schedule, buying more shares when prices are low and fewer when high.
Does lump sum beat DCA?
On average, lump sum wins about two-thirds of the time — but DCA protects against regret and panic selling.
How much of the final value is my contributions?
Early, most; over decades, growth dominates — the calculator separates both.
Cite this tool
BoringToolsKit. “DCA Investment Calculator.” boringtoolskit.com/dca-investment-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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