What is Bitcoin's security budget?

Bitcoin's security budget is the total amount paid to miners for adding blocks to the blockchain. That income pays for the electricity and machines behind bitcoin's computing power, and the more of it there is, the more expensive it becomes to overpower the network. The budget has two parts: newly created coins, called the block subsidy, and the fees users attach to transactions.

What is bitcoin miner revenue made of?

The 2008 white paper set out both parts. The first transaction in every block creates new coins for the miner who made it, and the miner also collects the fees on the transactions inside. The paper argued this reward makes following the rules more profitable for a would-be attacker than cheating. See how bitcoin mining works for the competition behind it.

As of October 2026, the subsidy is 3.125 BTC per block, set by the April 2024 halving. With roughly 144 blocks a day, that is about 450 new BTC a day, according to Spark's glossary.

How do the bitcoin block subsidy and fees compare?

Right now the subsidy dominates. The Block reported in November 2025 that fees had fallen to a 12-month low of less than 1% of miner income. A weekly report by btc.network for March 13 to 19, 2026, counted 1,884.375 BTC in subsidy against about 11.4 BTC in fees across 603 blocks, so fees were about 0.6% of revenue.

Fees can spike. Spark notes that during the April 2024 launch of Runes, a token system on bitcoin, one block carried about 37.6 BTC in fees. Our guide to Ordinals and Runes explains that activity. Spark puts the historical range of fees at under 1% to roughly 15% of miner revenue.

What happens to bitcoin security after halvings?

Every 210,000 blocks the subsidy is cut in half, as described in what is the bitcoin halving. The next cut, to 1.5625 BTC, is expected around 2028. Unless fees or the value of the coins paid to miners grow, each halving shrinks the budget measured in bitcoin. Eventually the subsidy ends altogether, the scenario covered in what happens when all bitcoin are mined.

The white paper anticipated this, saying the reward could one day come entirely from fees. Critics, as summarized by Spark, worry that fee income is volatile and that off-chain systems such as Lightning may reduce demand for on-chain transactions. Supporters counter that block space demand will grow, and that layer 2 networks still pay base-layer fees.

Proposals to change the system exist, but none has broad support. In a June 2026 discussion on the developer forum Delving Bitcoin, one participant proposed a small permanent block reward starting at a far-off halving. Developer Pieter Wuille called it a non-starter because it would break bitcoin's fixed supply, and others agreed the 21 million cap would be hard to touch. Others suggested ideas such as changing how block size is set or rewards from merged mining, which pays miners for securing other chains at the same time.

How the budget holds up over decades is unknown.