The average Briton retires at 65 (men) or 64 (women), with the State Pension age currently at 66 and rising to 67 between 2026 and 2028. A comfortable retirement in the UK costs approximately £50,000 per year for a couple and £34,000 for a single person, according to the Pensions and Lifetime Savings Association. The full State Pension provides £11,973 per year, leaving a significant gap to fill from private savings.
Under the traditional 4% withdrawal rule, a single retiree spending £34,000 per year needs £850,000 in savings. A couple spending £50,000 needs £1.25 million.
Bitcoin's power law model changes this calculation.
The power law floor has never been breached in over 15 years of daily data. It grows at approximately 37% per year (the Bitcoin Floor Rate). Your required Bitcoin stack is not fixed. It shrinks every year as floor-denominated expenses fall. A stack that barely covers 20 years of expenses today becomes effectively inexhaustible within a decade on the floor path alone.
Use the calculator below to model your personal scenario. Enter your current age, target retirement age, annual expenses in GBP, and existing Bitcoin holdings. The calculator runs Monte Carlo simulations across floor, trend, and ceiling price paths.
Key Finding: Based on 15+ years of power law data, a UK retiree spending £34,000 per year needs significantly less capital in Bitcoin than the £850,000 required under the traditional 4% rule, because the floor grows faster than expenses shrink in purchasing power.
Educational tool — not financial advice1. Bitcoin follows a power law. Giovanni Santostasi’s model (2024) fits 15+ years of daily price data to a log-log regression: log10(price) = a + b × log10(days since genesis). R² exceeds 0.95 — one of the strongest long-term fits in any financial asset. This is not a trendline drawn through noise; it is a statistical regularity with a physical basis in network adoption dynamics. Through network adoption, there are structurally more buyers than sellers at floor price levels — which is why the floor has held for 15 years and counting.
2. Log residuals mean-revert. The distance between the actual price and the power law trend (measured in log10 space) behaves like a spring: large deviations pull back toward the trend. This is modeled as an Ornstein-Uhlenbeck process — a well-studied mean-reverting stochastic process from physics. The implication: bubbles deflate, crashes recover, and the trend reasserts itself over time.
3. Volatility decays across regimes. Each Bitcoin halving cycle shows measurably lower volatility than the last. We calibrate separate residual distributions per cycle (2012–2016, 2016–2020, 2020–2024), each fitted with Student’s t-distribution (heavier tails than Gaussian to capture extreme moves). The trend is unmistakable: as Bitcoin matures, the swings shrink. Future cycles are projected to continue this decay.
4. Monte Carlo with power-law-specific design. We don’t use generic stock-market Monte Carlo. Every simulation parameter is derived from Bitcoin’s specific behavior: the OU mean-reversion speed, per-cycle t-distribution shape, and a hard downside clamp at −2σ (the empirical floor). Innovations are drawn from the fitted t-distribution, not a normal distribution — this preserves the fat tails that define crypto while respecting the mean-reversion that defines the power law.
5. 100,000 simulated price paths. Each path runs month-by-month from the user’s retirement age to life expectancy, deducting inflation-adjusted expenses and tracking stack depletion. 100,000 paths produce stable percentile estimates (p5 through p95) with minimal sampling noise. The probability you see in the ring is not a guess — it is the fraction of paths where your stack survives.
6. Floor-based math — the most rigid framework possible. The floor is defined as 0.42× the power law trend: the absolute worst-case price at any given date. Bitcoin has never traded below this level in its entire history. All retirement projections use the floor, not the trend or median. If the model is even approximately correct, this is the harshest assumption we can make. Measured from the floor, all volatility is on the upside.
7. The core inequality: stack × floor_growth > yearly expenses. This is the floor freedom test. When the floor’s annual growth alone exceeds your living costs, you never need to touch principal — even under the worst-case price path. The projection table shows this ratio climbing year by year. Once it crosses 100%, the floor alone sustains you indefinitely, and all volatility becomes pure upside.
8. Near-zero risk of ruin through first principles. Three compounding tailwinds work in your favor: (a) volatility decays cycle over cycle, (b) the floor rises deterministically via the power law, (c) your expenses in BTC terms shrink every year as the floor grows. The Monte Carlo confirms what the math predicts: for adequate stacks, 99%+ of all simulated futures survive to life expectancy. We cap displayed probabilities below 100% because finite simulations cannot prove absolute certainty — but the first-principles argument is even stronger than the simulation.
Verify it yourself. The full model — power law fit, residual distributions, per-cycle volatility histograms, and all 100,000 simulated price paths — is open for inspection at btcpowerlaw.nl. Every number on this page traces back to that data.
A personal walkthrough of your numbers, your strategy, and your timeline.
Send an EmailHMRC treats Bitcoin as a capital asset. Selling, swapping, spending, or gifting Bitcoin (except to a spouse) triggers a Capital Gains Tax event. The CGT rate is 18% for basic rate taxpayers and 24% for higher rate taxpayers (2025/26). The annual CGT exemption is £3,000. Losses can be offset against gains with no limit. Starting in 2026, exchanges must report transaction data to HMRC under OECD CARF rules. This calculator does not account for taxes. Consult a qualified tax adviser for your specific situation.
It depends on your annual expenses, current age, and target retirement age. A comfortable retirement in the UK costs approximately £34,000 per year for a single person or £50,000 for a couple. Using Bitcoin's power law floor model, the required stack is smaller than traditional models suggest because the floor grows at approximately 37% annually, reducing your BTC-denominated expenses over time.
Yes. Bitcoin is legal to own, buy, sell, and hold in the United Kingdom. It is regulated by the Financial Conduct Authority (FCA) as a cryptoasset. While Bitcoin cannot be held directly in a SIPP or ISA, you can gain exposure through regulated investment products.
The Bitcoin power law floor is the lower boundary of Bitcoin's long-term price channel, derived from a regression model spanning over 15 years of daily data. The floor has never been breached since Bitcoin's genesis on January 3, 2009. It currently grows at approximately 37% per year (the Bitcoin Floor Rate), though this rate decelerates over time as the network matures.
The calculator uses Giovanni Santostasi's power law model to project Bitcoin's floor, trend, and ceiling prices into the future. It then runs Monte Carlo simulations across these paths, modelling your annual withdrawals against projected BTC prices.
On the floor path alone, 1 BTC may not be sufficient for a full UK retirement at current floor levels. However, because the floor grows at approximately 37% annually while your BTC-denominated expenses shrink, the required stack decreases over time. The earlier you begin, the more the floor growth works in your favour.