DCA calculator

Data

Daily closing prices BTC/USD from the Bitstamp exchange, supplemented by the mempool.space price series.^[1],[2]We start in 2013 – before that, trading was very thin. Our server keeps the series up to date; if it is unreachable, the calculator uses the bundled data as of 05/10/2026. Our server fetches the current price from mempool.space, falling back to Bitstamp, Kraken or Coinbase. Your browser only talks to our server, never to third parties.

We calculate in US dollars because bitcoin is traded and quoted worldwide in dollars. If you save in euro, the euro-dollar exchange rate adds its own swings.

The calculation

• Purchase: once a month at the monthly close (daily close on the last day of the month, UTC), from the start month to the last completed month. “5 years” means exactly 60 purchases.
• Costs: deducted before buying: BTC bought = amount × (1 − costs) ÷ price. The levels come from our provider comparison (as of 28 Sep 2026). The default is 1% – the median of the savings plans; Bitpanda charges 0.99% plus a spread it does not quantify. Relai: first savings plan up to €100 with no service fee (0%), above that 1%. Cheaper: exchanges (Bitvavo 0.25%) and 21bitcoin (0% from day 8); more expensive: Coinfinity (1.5%).^{[3],[4],[5],[7],[6]}
• Value today: all BTC bought × current price. If the live price is unavailable, the last known price is used – and labelled as such.
• Return per year: internal rate of return (money-weighted), from 12 purchases.
• Largest portfolio decline: the steepest fall of the portfolio value from a high to the following low (monthly closes) – as you would have seen it. Because you kept paying in, it is milder than the price decline we also show (daily closes from the first purchase).
• Lowest point vs. paid in: the month in which your portfolio was furthest below the sum of your payments. Because of costs, even the first month is slightly negative.
• Worst starting month: we run every possible starting month in the period with at least twelve purchases up to today and show the weakest.

What the calculator does not show

• Taxes, withdrawal and custody costs, and price swings within a month.
• Inflation: all amounts are nominal.
• The future. Bitcoin has “survived” since 2013 – many other crypto assets have not. The large multiples of the early years cannot simply be extrapolated.

A savings plan is not a return trick: in studies of equity markets, investing a lump sum beat staggered investing in about two thirds of cases.^[8] Its value lies elsewhere – it fits a regular income and removes the question of the “right moment”.