A withdrawal plan can be read in three directions. How long do my holdings last at a fixed monthly amount? How much bitcoin do I need for a given amount? And the question of this page: which monthly amount uses the holdings up over a chosen period, either completely or down to a remainder that is meant to stay, as a buffer or for heirs?
How the calculation works
For every month of the period the calculator takes the bitcoin price assumed for that month. It then looks for the one starting amount at which the monthly sales add up to exactly the bitcoin available: holdings minus the chosen remainder. The amount can rise every year, for example to offset inflation; the examples use 2%. Because the result depends almost entirely on the price path, it is shown for four paths of the power law model.
Examples: spending down completely over 25 years
Start 14 October 2026, when Bitcoin closed at $81,576. Monthly amount in the first year, rising 2% a year:
| Holdings | Same ratio to trend as today | Price at the floor (cautious) | Price on the trend |
|---|---|---|---|
| 0.5 BTC | $858 | $716 | $1,415 |
| 1 BTC | $1,715 | $1,431 | $2,830 |
| 2 BTC | $3,430 | $2,862 | $5,660 |
The amount scales with the holdings: twice the bitcoin allows twice the monthly amount.
Examples: keeping a remainder
1 BTC, 25 years, 2% increase, with part of the holdings left untouched at the end:
| Remainder at the end | Same ratio to trend as today | Price at the floor (cautious) | Price on the trend |
|---|---|---|---|
| no remainder | $1,715 | $1,431 | $2,830 |
| 0.25 BTC | $1,286 | $1,073 | $2,123 |
| 0.5 BTC | $858 | $716 | $1,415 |
Keeping 0.25 BTC lowers the monthly amount from $1,715 to $1,286 in the main path. What that remainder would be worth at the end is shown in the calculator.
How much depends on the model
Without any price rise, the same plan allows only about $212 a month. The difference to $1,715 is the model's growth assumption. If the price does worse than the chosen path, the holdings run out before the period ends. The floor path is the cautious case; it has been undercut on about 1% of days since 2015. Why the model assumes such high prices, in plain words.
What the result leaves out
The model paths are smooth, the real price is not: selling in a deep drawdown costs more bitcoin than the smooth path assumes. Taxes, fees and spreads are not included. Treat the result as an order of magnitude, not as a plan, and not as investment advice.
The calculator in the live model works out the amount for your own holdings, period and remainder, in US dollars or euros. The same tab answers the other two questions: how long holdings last and how much bitcoin you need.
More guides
- Bitcoin Power Law Calculator: 7 Tools Explained
- How Much Bitcoin Do I Need to Retire? Power Law Calculator
- Bitcoin Power Law Formula Explained (a, b, R²)
- Bitcoin Power Law Floor Price by Year (2026–2040)
- Bitcoin Price Prediction 2030: Power Law Model Values
- Bitcoin Price Prediction 2035: Power Law Model Values
- Bitcoin Price Prediction 2040: Power Law Model Values
- Bitcoin Power Law vs Stock-to-Flow: Key Differences
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