About the DCA Backtest Calculator
Most DCA calculators fake it: they assume a constant return and draw a smooth curve no market has ever produced. This one replays your schedule against actual daily price history — Bitcoin from 2014, Ethereum from 2017, the S&P 500 from 1990 — contribution by contribution. Volatility is the whole point of averaging, so the simulation keeps it.
It answers the questions people actually argue about: what would $100 a week into Bitcoin have done since the 2021 top? Did lump-summing beat averaging over your window? How deep was the worst drawdown you would have had to sit through — and how far underwater were you at the low? The journey chart draws invested vs value so the emotional ride is visible, not just the ending.
Everything runs against a price table on our server, refreshed daily — no third-party calls at page load, and your inputs are never stored.
This is an educational backtest, not investment advice: one historical path predicts nothing, S&P figures exclude dividends (understating index returns ~1.5–2%/yr on long windows), and crypto’s past growth is widely considered unrepeatable. Talk to a licensed adviser before investing.
How to Use the DCA Backtest Calculator
Pick an asset, set the amount you would have invested and how often, and choose a start month — the results recalculate automatically against real daily closes. The most instructive experiment is deliberately picking a terrible start: January 2021 for Bitcoin, October 2007 for the S&P. Watch the invested and value lines cross and re-cross, note the marked drawdown trough, and read the worst-moment stat — that is the psychological price the final number never shows. Then compare the lump-sum card: same dollars, invested all at once on day one.
Why Fake-Math DCA Calculators Mislead
The typical online DCA calculator asks for an “expected annual return,” compounds it smoothly, and produces a serene exponential curve. That erases the mechanism that makes averaging interesting: with real volatility, a fixed dollar amount buys more units when prices crash, so two paths with identical average returns produce very different DCA outcomes depending on when the bad years land. A smooth-curve calculator cannot show sequence risk, drawdowns, or the lump-sum comparison honestly — which is to say it cannot show any of the things a person deciding between strategies needs to see.
DCA vs Lump Sum — What the Research Actually Says
Vanguard’s well-known studies found lump-sum investing beat spreading the money out in roughly two-thirds of historical windows, by about 2% on average — markets rise more often than they fall, so money invested earlier works longer. This tool will frequently show you exactly that, and says so rather than burying it. What the average hides is the distribution’s ugly tail: lump-summing the eve of a 50% crash is the regret people actually fear, and averaging cuts that tail dramatically. The honest framing: lump sum maximizes expected return; DCA buys insurance against terrible timing and, more importantly, is a plan people actually stick to.
Volatility Is the Engine
Run the same schedule on the S&P 500 and on Bitcoin and compare the gap between average cost and final price. The index, with its comparatively gentle swings, gives DCA little to grab; average cost lands near the midpoint of the path. Bitcoin’s 70–80% drawdowns are where averaging shines mechanically — the fixed $100 buys three times the units at the bottom — and where it fails behaviorally, because continuing to buy through an 80% crash is precisely what most people cannot do. The worst-moment stat exists to make that conversation concrete.
Max Drawdown and the Behavior Gap
Fund returns and investor returns differ — Morningstar’s “Mind the Gap” research measures the shortfall at roughly 1–2% per year, caused mostly by buying after rallies and selling into declines. Max drawdown is the best single predictor of whether a strategy will trigger that behavior in you. A useful exercise with this tool: find the deepest drawdown in your chosen window, then imagine the account statement at the trough — invested $29,200, worth $14,000. If that statement would have made you stop contributing, the backtest’s final number was never available to you.
Methodology and Data Sources
Contributions execute at the daily close on or after each scheduled date (weekends and holidays roll forward to the next trading day). Price history: Bitcoin daily closes from September 2014, Ethereum from November 2017, the S&P 500 index level daily from 1990 — refreshed nightly. Start dates before an asset’s history clamp forward with a visible note. S&P results use the price index, not total return: dividends would add roughly 1.5–2% per year, so long-window index outcomes shown here are conservative. Annualized return is computed on total invested over the full window — a simplification (money entered gradually), shown for scale rather than as an IRR.
Thinking through the saving side too? Pair this with the Compound Interest Calculator and the FIRE Calculator. Browse all Personal Finance tools for more.
Frequently Asked Questions
What is dollar-cost averaging?
Investing a fixed dollar amount on a fixed schedule regardless of price. Because the amount is constant you automatically buy more units when prices are low and fewer when high, which smooths your average cost and removes timing decisions. Its real benefit is behavioral — it keeps people invested through drawdowns.
Does DCA beat lump-sum investing?
Historically, lump sum wins about two-thirds of the time in rising markets simply because money is invested longer — Vanguard's research puts the average edge near 2 percent. DCA wins in falling or choppy windows and dramatically reduces worst-case regret. This tool shows both for your exact window rather than the average.
How accurate is the price data?
Daily closing prices: Bitcoin from September 2014, Ethereum from November 2017, and the S&P 500 from 1990, refreshed daily. Dividends are not reinvested in the S&P figures, so long-window index results understate total return by roughly 1.5 to 2 percent per year — the methodology note on the page covers this.
What does max drawdown tell me?
The largest peak-to-trough decline your portfolio value experienced during the window. It is the honest measure of what you would have had to sit through — a strategy with a great final number and an 80 percent drawdown is one most people abandon at the bottom, which is why the tool marks it on the chart.
Should I use these results to pick my investments?
No. Backtests describe one historical path; they do not predict returns, and crypto's past growth rates are widely considered unrepeatable. This tool exists to teach how averaging, volatility, and time interact. Talk to a licensed financial adviser before making investment decisions.
