The question behind every withdrawal plan is the reverse of a savings plan: not "what will my bitcoin be worth?" but "how much do I need so that a fixed monthly amount lasts long enough?" The answer depends almost entirely on the price path, so the calculator does not give one number but four — one for each price path of the power law model.
How the calculation works
For every month of the chosen period, the calculator takes the withdrawal for that month and divides it by the bitcoin price assumed for that month. The sum of all these monthly amounts is the bitcoin needed. Months that already lie in the past use the actual daily close. The withdrawal can rise every year, for example to offset inflation; the examples below use 2%.
Examples: 25 years from today
Start 14 October 2026, 25 years, withdrawal rising 2% a year. On that day Bitcoin closed at $81,576, 0.60 times the trend value.
| Per month | Same ratio to trend as today | Price at the floor (cautious) | Price on the trend |
|---|---|---|---|
| $1,000 | 0.58 BTC | 0.70 BTC | 0.35 BTC |
| $2,000 | 1.17 BTC | 1.40 BTC | 0.71 BTC |
| $5,000 | 2.92 BTC | 3.49 BTC | 1.77 BTC |
Translated into today's money: 1.17 BTC cost $95,123 at today's price; the cautious floor path needs 1.40 BTC, which cost $114,004 today.
Why so few bitcoin?
The small numbers follow from the model's growth assumption. If the price keeps today's ratio to trend, one bitcoin costs about $220,000 in 2030, $2,100,000 in 2040 and $11,000,000 in 2050. Every later withdrawal therefore needs only a small fraction of a bitcoin. Without any price rise, the same plan would take 9.42 BTC instead of 1.17 BTC. The gap between the two is the model's growth assumption, and the further the withdrawals lie in the future, the more the result depends on the model continuing to hold. Why the model assumes such high prices, in plain words.
Examples: 25 years from 2035
Withdrawals starting on 1 January 2035 need fewer bitcoin, because every path assumes a higher price by then. The same amounts, 25 years, 2% increase:
| Per month | Same ratio to trend as today | Price at the floor (cautious) | Price on the trend |
|---|---|---|---|
| $1,000 | 0.09 BTC | 0.11 BTC | 0.06 BTC |
| $2,000 | 0.19 BTC | 0.22 BTC | 0.11 BTC |
| $5,000 | 0.47 BTC | 0.56 BTC | 0.28 BTC |
The four price paths
- Same ratio to trend as today: the price stays at today's multiple of the trend line. This is the main result in the calculator.
- Price at the floor: the price runs along the lower edge of the corridor, which it undercut on about 1% of days since 2015. This is the cautious case.
- Price on the trend: the price follows the trend line exactly.
- Price stays at today's level: no growth at all. In the calculator this shows how much the model's growth assumption does to the result.
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, and the order of good and bad years matters. Taxes, fees and spreads are not included either. The floor path covers part of this risk, not all of it. Treat the result as an order of magnitude, not as a plan, and not as investment advice.
The calculator in the live model recalculates every value for your own amount, period and start date, in US dollars or euros. A second calculator does the opposite: how long a given amount of bitcoin lasts.
More guides
- Bitcoin Power Law Calculator: 6 Tools Explained
- 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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