Lump sum vs
dollar-cost averaging.
If you have a large amount to invest, should you deploy it all at once or spreadSpreadThe gap between two prices or rates. In trading, it is the difference between the price buyers pay (ask) and the price sellers get (bid). Many Bitcoin apps and money-transfer services also build a markup into the price they quote you, a cost on top of the advertised fee even when that fee is $0.Full definition it across months? Vanguard research (2012) found lump sum beats DCA about two-thirds of the time historically. This tool backtests a specific scenario using approximate monthly closes.
The question it answersShould I invest a lump sum all at once or spread it out with dollar-cost averaging?
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Looking for something close? Bitcoin DCA Calculator: a fixed amount every week or month from a chosen start year, priced with daily closes, with a chart, a lump-sum comparison and CSV export. Sats Accumulator: how many months of buying it takes to reach a sats target.
Historical, not a forecast. This replays past data. It does not predict what happens next.
What this tool assumes
- S&P 500 backtest uses approximate monthly price-index closes (dividends excluded).
- Bitcoin backtest uses month-end closes generated at every build from the site's CoinMetrics snapshot (data/btc.json); no dividends. Data through 2026-09-19.
- DCA schedule divides the lump sum equally across the selected months, starting at the start-year date.
- Uninvested DCA cash earns 0% while waiting to be deployed (no money-market yield), which biases results toward lump sum.
- Endpoint: S&P data runs through 2026-08; BTCBitcoin (BTC)The ticker symbol for Bitcoin, used on exchanges and in price quotes.Full definition through 2026-08.
- No transaction fees, taxes, or rebalancingrebalancingBuying and selling assets to restore your target portfolio split after market movements cause drift.Full definition are modeled.
- This is a single historical path. For probabilistic rollouts, see the Vanguard 2012 paper linked below.
Historical S&P and BTC monthly closes are approximate. Educational only; not financial advice.
HOW THIS IS CALCULATED
This tool runs entirely in your browser: no data is sent to any server. The assumptions and default values behind the result are listed under “What this tool assumes” on this page. Verify the methodology or inspect the source code in your browser's dev tools.
Where to go from here
Calculators are educational estimates, not financial advice. Disclosures · How pages are reviewed