What this chart shows
On every purchase date — weekly or monthly, starting from the date you choose — this page buys your fixed dollar amount of Bitcoin at that day's actual historical price, and accumulates the running total. The chart plots your portfolio's mark-to-market value against the flat line of what you actually put in.
All of this runs against the same daily price history used everywhere else on this site — there's no separate "backtested returns" dataset, and no survivorship bias, since Bitcoin's full price history back to 2010 is what's being replayed.
How to read it
The stat cards above the chart summarize the outcome: total invested, current portfolio value, return, your average cost basis versus today's price, and total BTC accumulated. Change the start date, frequency or amount and re-run — the whole point is to let you test your own assumption instead of reading someone else's cherry-picked example.
Limitations
This assumes every purchase executes exactly at that day's Coin Metrics reference price with zero fees, slippage or spread. Real exchange fees (often 0.1%-1.5% per trade) and imperfect timing would reduce actual returns versus what's shown here.
A backtest over any historical window is a description of that specific window, not a forecast. Choosing a start date right before a crash or right before a rally produces wildly different results from the same strategy — that sensitivity is itself worth noticing, not something to average away.
"Weekly" and "monthly" here are fixed calendar steps from your chosen start date, not calendar-aligned (e.g. not necessarily the 1st of each month). This doesn't materially change results but means exact purchase dates may differ slightly from a real recurring-buy plan on an exchange.