The quick view
Below are two clean, reusable charts you can embed or download.
- Halving timeline (2012–2024): Download PNG · Download CSV
- Hashrate milestones (2021–2025): Download PNG · Download CSV
The fourth halving cut block rewards to 3.125 BTC on April 20, 2024 (block 840,000). Miners also collected a record fee haul on the halving block as users competed for inclusion. In 2025, network hashrate printed fresh records above 1 zettahash per second, despite cyclical squeezes on miner revenue.
Why these milestones matter
Halvings compress issuance, protocol upgrades change throughput and fee dynamics, and policy shocks (like China’s 2021 ban) can abruptly move hashrate across borders. Understanding the sequence helps explain miner profitability cycles, energy debates, and the “security budget” that blends subsidy and fees.
Timeline: 2015–2025 highlights
2016: Second halving
Block subsidy fell from 25 BTC to 12.5 BTC on July 9, 2016.
2017: SegWit activation and scaling groundwork
Segregated Witness (SegWit) locked in during August and activated on August 24, 2017, fixing malleability and enabling the block-weight model and future layer-2s.
2020: Third halving
On May 11, 2020, the reward dropped to 6.25 BTC, tightening issuance through the 2021 bull cycle.
2021: China’s crackdown, global migration, and Taproot
China’s regulators moved to ban mining; the country’s share collapsed and hashrate temporarily plunged before relocating to the U.S., Kazakhstan, and elsewhere. In November, Taproot activated at block 709,632, improving privacy and flexibility.
2023: Ordinals and fee spikes
Inscriptions and BRC-20 activity pushed mempools to extremes and drove average fees to multi-year highs in December 2023, temporarily boosting miner revenue from fees.
2024: Fourth halving and historic fee block
At block 840,000 (April 20), subsidy halved to 3.125 BTC—and users paid roughly 37.7 BTC in fees, totaling about 40.7 BTC (~$2.6M) for the halving block.
2025: Record hashrate, tougher economics
By mid-August 2025, hashrate set an all-time high near 1.239 ZH/s; JPMorgan estimated early-August average at ~937 EH/s. Higher difficulty and choppy fees keep pressure on “hashprice” (revenue per unit of hashrate).
Chart 1 explained: Block subsidy over time
The subsidy halves roughly every 210,000 blocks. The four confirmed dates are November 28, 2012; July 9, 2016; May 11, 2020; and April 20, 2024. Rewards declined from 50 → 25 → 12.5 → 6.25 → 3.125 BTC per block, reducing new supply and shifting more miner income toward transaction fees over the long run. See the CSV if you want to recreate the plot.
Chart 2 explained: Hashrate milestones
The polyline marks selected points:
- Mid-May 2021: ~180 EH/s pre-crackdown
- Late June 2021: ~90 EH/s during the trough
- Aug 14, 2025: ~1.239 ZH/s all-time high
- Aug 18, 2025: ~937 EH/s early-month average
These illustrate the 2021 shock and the multi-year climb to 2025 records. For live series, reference public hashrate dashboards.
Protocol upgrades that shaped miner economics
SegWit (2017)
By separating witness data, SegWit increased effective capacity and fixed malleability—laying groundwork for the Lightning Network and changing how blockspace is measured and priced.
Taproot (2021)
Taproot’s activation at block 709,632 improved privacy for complex spends and added script flexibility, which later intersected with inscription activity and on-chain experiments.
Fees as the future “security budget”
Ordinals and other high-demand periods show that fees can, at times, rival or exceed subsidy. The halving block in April 2024 paid ~37.7 BTC in fees on top of the new 3.125 BTC subsidy, a dramatic example of fee-driven miner revenue.
Migration and energy: the big debate
The 2021 crackdown forced miners out of China, with measurable shifts in the Cambridge Bitcoin Mining Map and electricity-use research. Cambridge’s CBECI continues to track methodology and consumption estimates that policy analysts often cite when debating energy mix, emissions and grid impacts.
Operator takeaways for the next cycle
Track hashprice, not just BTC price
Hashprice—revenue per unit of hashrate—hit post-halving lows in 2024 as difficulty climbed and fees normalized. It’s a better single-metric proxy for miner cash flow.
Expect fee volatility
Activity spikes (e.g., inscriptions) can swing fees quickly. Build treasury plans that don’t rely on persistent fee windfalls.
Build policy and grid flexibility into siting
Regulatory shocks can move entire fleets; grid rules and interconnection lead times are now strategic variables for new deployments.
FAQs
When were the four halving dates, and what are today’s rewards?
November 28, 2012; July 9, 2016; May 11, 2020; and April 20, 2024. The current subsidy is 3.125 BTC per block.
Did China really “kill” Bitcoin mining in 2021?
It caused a historic drop and relocation. Reported Chinese share fell toward zero in mid-2021; hashrate later recovered as miners moved to other jurisdictions.
Why did fees spike so much in late 2023 and around the 2024 halving?
Ordinal inscriptions drove intense competition for blockspace in late 2023, and the halving block was uniquely valuable, prompting users to pay record fees for inclusion.
