Bitcoin security budget · the figures · this is the dated snapshot for 2026-09-11
Bitcoin’s security budget, in numbers
As of 2026-09-11: Bitcoin pays 0.82% of market cap a year for security; the gap to a 1% target is $2.75B a year; fees are 0.63% of miner revenue; the ratio falls to 0.41% after the 2028 halving regardless of price.
The whole argument in one line: the ratio has fallen from over 100% to 0.82%, stepping down at every halving, and the next step is already scheduled for ~April 2028. The record, the method, and the 6,446-row daily dataset →
Start here
- What is Bitcoin's security budget?
Bitcoin's security budget is the total paid to miners for securing the chain: the block subsidy plus transaction fees. Over the trailing year to 2026-09-11 it was $14.30B, about 0.82% of Bitcoin's $1.55T market capitalisation a year. The subsidy is 3.125 BTC per block and halves toward zero around 2140; fees were 0.63% of miner revenue over the last 30 days. - How much does Bitcoin spend on security per year?
$14.30B over the trailing 365 days to 2026-09-11, summing each day at that day's price. On a spot run-rate basis it is about $12.77B a year. Either way it is about 0.82% of a $1.55T market capitalisation, or $0.0082 of security spending a year for every $1 of market cap. - What is the Bitcoin Security Index (BSI)?
The BSI is annualised miner revenue divided by market capitalisation: what Bitcoin pays for its own security as a share of what that security protects. As of 2026-09-11 it is 0.82%. It falls to 0.41% after the ~April 2028 halving, 0.21% after ~2032 and 0.11% after ~2036, with no price assumption entering. - When does Bitcoin's block subsidy end?
The subsidy halves roughly every four years and reaches zero around 2140. It is 3.125 BTC per block today and falls to 1.5625 BTC at the ~April 2028 halving. The security budget falls with it: from 0.82% of market capitalisation a year to 0.41%, then 0.21% after ~2032 and 0.11% after ~2036.
The gap
- How big is Bitcoin's security budget gap?
As of 2026-09-11, Bitcoin pays about 0.82% of its market capitalisation a year for security (annualised miner revenue over market cap). Against a 1% target, the gap is $2.75B a year, about $7.5M a day or $52.4K per block, at a $1.55T market cap. - What is Bitcoin's security budget after the 2028 halving?
About 0.41% of market cap a year after the ~April 2028 halving, then 0.21% after ~2032 and 0.11% after ~2036, from today's 0.82% (as of 2026-09-11). No price assumption enters: price is in both numerator and denominator and cancels. 0.41% is below the 0.5% bottom of Lyn Alden's published band. - Is Bitcoin's security budget actually a problem, or is it FUD?
The arithmetic is not disputed: Bitcoin pays 0.82% of market capitalisation a year for security today and 0.41% after the 2028 halving, with no price assumption. What is disputed is whether that is too little. Published estimates of an adequate spend run from 0.5% to 1.5% of market cap a year. At the bottom of that range there is no gap today; from 2028 there is one at any floor in it. - What happens to Bitcoin's security when the block subsidy ends?
The subsidy halves roughly every four years toward zero around 2140; today it is 3.125 BTC per block. Fees are 0.63% of miner revenue over the last 30 days (as of 2026-09-11). For fees alone to close today's gap to a 1% target they would need to reach about 18% of miner revenue permanently, roughly 29× today's level. Bitcoin's longest stretch above 20% is 40 days. - Why do different sources give different figures for Bitcoin's security budget?
Because the same ratio can be built three defensible ways, and they disagree. Trailing-year revenue over spot market cap gives 0.92%; trailing-year revenue over average market cap gives 0.86%; spot run-rate revenue over spot market cap gives 0.82%. These pages publish 0.82%, the most conservative of the three, and publish the other two beside it. - Has Bitcoin's security budget fallen over time?
Yes, by more than two orders of magnitude. As of 2026-09-08, Bitcoin's security budget was 0.82% of market capitalisation a year, on a trailing-year basis. It was 25.03% at the first halving in 2012-11, 8.41% at the second halving in 2016-07, 3.66% at the third halving in 2020-05, 1.81% at the fourth halving in 2024-04. The ratio steps down at every halving and drifts between them. The full daily series, 6,446 rows from 2009-01-15 to 2026-09-08, is published as CSV and JSON under CC BY 4.0.
Fees
- What share of Bitcoin miner revenue comes from fees?
0.63% over the trailing 30 days, as of 2026-09-11; about $1.8K per block on a trailing-year basis. The all-time peak day was 2024-04-20 at 75.2% of miner revenue; the best 30-day window was January 2018 at 26.2%. - Can transaction fees alone replace Bitcoin's block subsidy?
To bring today's security budget to a 1% target on fees alone, fees would need to reach about 18% of miner revenue permanently, roughly 29× today's 0.63%. Bitcoin has never sustained that: its longest run above 20% of miner revenue is 40 days, ending 2018-01-31, and it has never spent a sustained stretch above 30%. - When were Bitcoin's highest transaction fee periods?
The highest single day on record is 2024-04-20 at 75.2% of miner revenue. The best 30-day window is January 2018 at 26.2%. The longest stretch above 10% of miner revenue is 100 days, ending 2018-02-15; above 20%, 40 days; above 30%, none. Today's trailing-30-day figure is 0.63%.
What could close it
- What are the proposed fixes for Bitcoin's security budget?
Six are seriously proposed: let fees grow, rely on price appreciation, scale on-chain volume, add a tail emission, tax idle coins, or pay miners from outside consensus. The first needs fees at about 18% of miner revenue, 29× today's level. The middle four require a consensus change or an assumption Bitcoin's record does not yet support. Only the last can be tried without changing Bitcoin. - What is a second subsidy for Bitcoin miners?
A second subsidy is any reward paid to whoever mines a Bitcoin block that does not come from Bitcoin's own issuance. Because it sits outside consensus it needs no protocol change, cannot dilute bitcoin, and can fail without taking anything with it. Merged mining is the oldest form; $NAT is one current implementation, paying about 5.2% of its market capitalisation a year to the winning coinbase address. - What is $NAT?
$NAT is a token whose issuance is credited to the address that mined each Bitcoin block, so it pays miners alongside the block subsidy and fees. It has done so since block 885,588 in February 2025. Its emission is about 5.2% of its own market capitalisation a year, so $1 of $NAT market cap pays about $0.052 a year to miners, against $0.0082 for $1 of Bitcoin market cap. - How much of Bitcoin's security budget gap could $NAT fill?
At a $1B market capitalisation, $NAT's emission pays about $52.0M a year to miners, which is 1.9% of today's $2.75B annual gap and about half of the yearly average Bitcoin earns in fees. Covering the whole gap at today's emission rate would take a market capitalisation near $52.00B. $NAT's market capitalisation on 2026-09-11 was $29.9M. None of this forecasts that any of those figures is reached.
Every figure, its basis, its date
| Figure | Value | Basis |
|---|---|---|
| Security spend, share of market cap | 0.82% | spot run-rate revenue (last 1,008 blocks) over spot market cap |
| Gap to 1%, per year | $2.75B | (1% − 0.82%) × $1.55T |
| Gap, per day / per block | $7.5M / $52.4K | /365; /52,560 |
| Fee share of miner revenue, 30 days | 0.63% | fees over subsidy + fees |
| Fee share needed to close the gap | 18% (29×) | held permanently |
| Longest run above 20% | 40 days | 30-day smoothed; ended 2018-01-31 |
| Best 30-day window ever | 26.2% | January 2018 |
| Peak single day | 75.2% | 2024-04-20; 304% of the subsidy alone |
| Ratio after ~Apr 2028 / ~2032 / ~2036 | 0.41% / 0.21% / 0.11% | subsidy halved on schedule, fee component held; price-independent |
| Post-2028 gap at the best fee month ever | $4.68B | Jan 2018 fee dollars held flat |
| BTC price / market cap | $77,286 / $1.55T | CoinGecko, 2026-09-11 |
Three bases
| Basis | Ratio | Gap / yr | Market cap to cover it |
|---|---|---|---|
| Trailing-year revenue over spot market cap | 0.92% | $1.23B | $23.58B |
| Trailing-year revenue over average market cap | 0.86% | $2.12B | $40.68B |
| Spot run-rate revenue over spot market cap (published) | 0.82% | $2.75B | $52.95B |
Three ways to measure the same ratio, all published. None of the three closes the gap.
Where NAT comes in. NAT is a token credited to the winning miner of every Bitcoin block, computed from the block header. It issues about 5.2% of its supply a year, so its contribution to the gap is arithmetic: at a $1B market cap it would cover about 1.9% of today’s gap; the cap that would cover all of it is about $53.0B. That is a conversion between two market capitalisations, not a forecast. The full sizing, with its caveats, is on the FAQ.