Dollar cost averaging calculator

How this calculator works

Dollar cost averaging (DCA) means investing a fixed dollar amount on a regular schedule—weekly, bi-weekly, monthly, or annually—regardless of whether markets are up or down. You buy more shares when prices are low and fewer when prices are high, which smooths your average purchase price over time.

This calculator projects long-term outcomes from your contribution schedule:

• Total contributions — including an optional starting lump sum
• Total growth — investment returns on contributions and accumulated balance
• Final portfolio value — contributions plus growth at your assumed return rate
• Effective annualized return — the rate that would produce your ending balance from total dollars invested
• Year-by-year table — contributions, growth, and balance each year
• Stacked chart — visual split between money you put in vs. returns earned over time

Optional annual contribution increases model raises—useful when you expect salary growth to boost investing over time. When you enter both a lump sum and ongoing contributions, a comparison panel shows lump-sum-only vs. DCA paths side by side.

Returns are pre-tax; fund fees, trading costs, and taxes on dividends or gains are not included. Adjust the return assumption downward if you want a conservative planning view.

For simpler lump-sum or flat-contribution growth without DCA framing, see the compound interest calculator. For retirement-specific projections with inflation adjustment, use the retirement projection calculator.

What affects the result

DCA projections depend on how much you invest, how often, for how long, and what return you assume—not on short-term market timing.

• Contribution amount and frequency — More money invested sooner compounds longer. Weekly vs. monthly contributions differ slightly within a year but matter less than total annual amount and return assumption.
• Return assumption — 7% is a common long-term U.S. stock market planning figure after inflation in many educational models—it is not a guarantee. Stress-test at 5–6% for conservative goals.
• Investment period — Longer horizons amplify the gap between total contributions and total growth in the chart. Early years look contribution-heavy; later years show growth dominating if returns stay positive.
• Annual contribution increases — Raising $500/month by 3% each year boosts ending value versus flat contributions without changing your starting amount.
• Initial lump sum — A starting balance shifts the contributions-vs.-growth visual earlier. Large lump sums can dominate ending wealth even with modest ongoing DCA.
• Lump sum vs. DCA comparison — When both are entered, the panel illustrates a common debate: investing a windfall immediately vs. spreading entry over time.

Pair with the investment fee calculator to see how expense ratios reduce net returns, and the savings goal calculator when you need a target balance by a specific date rather than an open-ended projection.

Real-world examples

Example 1: Steady monthly investing. You invest $500/month for 20 years at 7% assumed return with no lump sum. Contributions total $120,000; growth often exceeds contributions over long periods—the stacked chart makes that visible. Run the same inputs at 5% and 8% to bracket uncertainty.

Example 2: Lump sum plus paycheck investing. You receive $10,000 and add $200/month for 15 years at 6%. The lump sum vs. DCA panel compares investing the $10,000 immediately vs. hypothetical phased entry. Historically lump sum often wins; DCA still reflects how most people invest from each paycheck.

Example 3: Annual raises on contributions. Starting at $400/month and increasing 3% per year for 25 years at 7% produces a higher ending balance than flat $400/month—modeling career wage growth without changing your initial budget.

Example 4: Bi-weekly 401(k) deferrals. $250 every two weeks approximates $6,500/year—close to IRA limits in some years and a common payroll rhythm. Frequency within the year matters less than maintaining consistency through market downturns.

Example 5: Starting late. Beginning $600/month at age 45 for 20 years at 6% illustrates catch-up DCA. Ending balance depends heavily on contribution rate because the time window is shorter—compare with the retirement projection calculator for retirement-specific framing.

Common mistakes

Expecting DCA to beat lump sum historically. Research often shows lump sum investing outperforms DCA over long periods because markets rise more often than they fall. DCA still helps investors who invest from each paycheck and reduces regret if markets drop right after a large purchase.

Using optimistic return assumptions. A single 10% figure can overstate ending wealth. Run 5%, 6%, and 7% scenarios for planning ranges, especially for goals within 10 years.

Ignoring fees and taxes. Expense ratios of 0.50% or 1% compound against you. Taxable account dividends and rebalancing create drag not shown here—reduce the return input or use the investment fee calculator.

Stopping contributions in downturns. DCA works best when you keep investing through volatility. Pausing during drops misses lower prices—the behavioral benefit of DCA assumes consistency.

Confusing DCA with guaranteed lower risk. DCA smooths entry timing; it does not eliminate market risk on money already invested. A falling market still reduces portfolio value after shares are purchased.

Treating effective annualized return as future promise. The calculated rate summarizes what happened in the model given inputs—it is not a forecast of next year's performance.

When to use this calculator

Use it to visualize long-term investing habits, teach how contributions and growth interact, or compare lump sum vs. periodic investing when you hold both options—inheritance, bonus, or sale proceeds plus ongoing salary deferrals.

Reach for it when explaining why starting early matters, how raising contributions over time accelerates outcomes, or why the stacked chart bends upward in later years when compounding dominates.

Pair with the compound interest calculator for non-DCA lump-sum math, the investment fee calculator for cost drag, and the retirement projection calculator for inflation-adjusted nest-egg views.

Skip this tool for market-timing strategies, tax-lot harvesting analysis, or withdrawal-phase planning—those need different models.

Related calculators

• Compound interest calculator — lump-sum and contribution growth without DCA scheduling emphasis.
• Savings goal calculator — solve for monthly savings needed to hit a target by a deadline.
• Retirement projection calculator — project retirement balances with contributions and optional inflation adjustment.
• Investment fee calculator — quantify how expense ratios reduce wealth over decades.

Related guides

• Compound growth basics — why time, reinvestment, and consistent contributions build wealth.
• Simple vs. compound interest — how compounding differs from linear growth in savings and loans.