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Satoshi Institute · backtest

Dollar-cost averaging, backtested

Pick an amount and a cadence. See what steady buying would have become, and what you'd have done buying something else on the same schedule.

Buy each time
$
Cadence
Starting
Strategy
Compare against
BTCETHSOL

Putting $100 into Bitcoin weekly since Jun 2021

$39,7621.51×from $26,300 in

That's 0.6316 BTC at an average price of $41,643.

InvestedBTC value
BitcoinBTC
Invested$26,300
Worth today$39,762
Return+51% · 1.51×
CAGR+8.5%
Accumulated0.6316 BTC
Avg cost$41,643

What this leaves out. Prices are weekly closes from CoinGecko. No fees, no spreads, no taxes, and no slippage, so real-world returns run lower. Past performance is not a forecast, and a different start date can flip the story entirely. This is a backtest for understanding, not advice.

Equities are next. The BTC-vs-S&P comparison every DCA tool needs requires an equities data feed wired through the server layer. The engine here already accepts new assets. Stocks and gold drop in once that feed is connected.

FAQ

Does DCA actually work, or is this just survivorship bias?

The backtest is real — but the question underneath it is right to ask.

DCA works in volatile assets for a mechanical reason: you buy more units when price is low and fewer when it's high, so your average cost per unit is always below the arithmetic average of prices over the period. This is Jensen's inequality applied to purchasing, not an opinion. The math is not in dispute.

The survivorship bias critique is more serious. Bitcoin is the asset that survived and appreciated dramatically. A DCA backtester built on an asset that went to zero would show 100% loss regardless of cadence. The tool doesn't tell you Bitcoin will keep appreciating — it tells you what disciplined buying into Bitcoin's actual history would have produced.

What the backtester is and isn't:

  • It is a precise accounting of historical outcomes under a specific buying rule
  • It is not a forecast, and past CAGR numbers are not expected future returns
  • The comparison to lump-sum is genuinely informative: in strongly trending assets, lump-sum often wins; in volatile ones, DCA reduces timing risk at the cost of some upside

The most honest use of this tool is stress-testing your assumptions — picking a start date that includes a major drawdown (2021, 2022) and seeing what the numbers look like, not just the favorable periods.

Methodology

Simulates dollar-cost averaging by buying a fixed dollar amount on a repeating schedule and accumulating units at each scheduled close price.

Total Invested
I = Σ C (C per period × n periods)
Units Acquired (per period)
u_i = C ÷ P_i
Total BTC Accumulated
U = Σ u_i
Average Cost Basis
ACB = I ÷ U
Portfolio Value
V = U × P_spot
ROI
ROI = (V − I) ÷ I × 100%
Money-Weighted CAGR
CAGR = (V ÷ I)^(1 ÷ years) − 1

DCA gives up upside in a strict uptrend (later dollars buy fewer units) but caps regret in a drawdown. Its real value is behavioral — deploying capital on a schedule someone will actually stick to.

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