Fractal Bitcoin has completed its first halving at block 2,100,000, cutting the network’s block reward to 6.25 FB as the FIP-102 consensus upgrade takes effect and sets aside an equivalent 6.25 FB emission budget for future distribution on the Bitcoin mainnet.
The project said in a September 8 post on X that the halving had completed successfully, with network nodes and indexing services operating normally during the first ten minutes after activation. Fractal said it will continue monitoring the network and asked users experiencing service-related problems to contact the team.
## What FIP-102 actually did
FIP-102 changes how future FB emissions are distributed while preparing the token for distribution on Bitcoin. The proposal does not raise FB’s total supply and does not create a separate supply for tokens distributed through Bitcoin.
Under the proposal, Fractal’s first scheduled halving reduced the block reward from 25 FB to 12.5 FB. The upgrade simultaneously brought forward the network’s second halving, cutting the reward again to 6.25 FB. The remaining 6.25 FB per Fractal block equivalent has been allocated to a Bitcoin mainnet distribution budget. That allocation will not be distributed at its full rate immediately; the project is planning a progressive rollout after the upgrade.
The existing reward structure between Merged Mining, Permissionless Mining and Index Mining remains intact. Blocks on the Fractal side will continue to be assigned to the three mechanisms at a 1:1:1 ratio, meaning one block in each three-block cycle goes to each category.
Before the halving, Fractal emitted 25 FB per block, so each of the three mechanisms received an average allocation of roughly 8.33 FB per block measured across the three-block cycle. Following FIP-102, each eligible Fractal block now carries a 6.25 FB reward, and averaged across the block sequence, Merged Mining, Permissionless Mining and Index Mining each account for approximately 2.0833 FB per Fractal block.
## A second emission path on Bitcoin itself
The second 6.25 FB allocation will eventually be distributed to users through eligible activity on the Bitcoin mainnet. FIP-102 establishes the emission budget, while the specific activities, technical architecture and distribution rules are being left to an upcoming FIP-103 proposal.
A 1:1 conversion mechanism between FB on Fractal and FB on Bitcoin mainnet is planned under the same framework. Converting a token between the two environments will not generate an extra unit of FB, according to the proposal, keeping both versions within one unified supply.
The rollout timeline is measured in quarters. Bitcoin-mainnet distribution is planned progressively over roughly three months, research and implementation work will continue for three to six months, testing is scheduled to begin in the fourth quarter of 2026, and a full rollout is targeted for the first quarter of 2027. FIP-103 will provide the remaining technical details, including eligible interactions, distribution mechanisms, rollout requirements and the conversion process between Fractal and Bitcoin.
At full rollout, the combined target emission budget will remain equivalent to 12.5 FB per Fractal block, split evenly between 6.25 FB in Fractal-side block rewards and a 6.25 FB equivalent budget for Bitcoin-mainnet distribution. Future reward milestones will follow the revised schedule: the next Fractal halving is set for block 4,200,000, after which the target allocations for both the Fractal and Bitcoin distribution paths are expected to decline proportionally unless a later Fractal Improvement Proposal changes the mechanism.
## Why the merged-mining base matters
The mainnet distribution plan expands on Fractal’s existing relationship with Bitcoin miners. In April 2025, Fractal added Foundry to its merged-mining network, giving the protocol access to computing power equivalent to 93 percent of Bitcoin’s hashrate at the time. Because Fractal and Bitcoin both use SHA-256, miners can secure the two networks through merged mining without dedicating separate computing power to each chain.
Fractal uses its Cadence Mining model to prevent merged miners from receiving the entire block reward. The model divided rewards between Bitcoin merged miners and permissionless participants before Index Mining was incorporated into the current three-way allocation. Binance Pool began supporting Fractal Bitcoin merged mining in November 2024, allowing Bitcoin miners using the service to receive FB rewards in external wallets, though Binance said at the time that support for FB mining did not mean the exchange planned to list the token.
The halving follows the same basic supply mechanism used by Bitcoin, where scheduled halvings periodically reduce new issuance. Bitcoin itself currently pays miners 3.125 BTC per block following its April 2024 halving, with its next reward reduction expected around 2028. Bitcoin’s block subsidy falls by 50 percent every 210,000 blocks, slowing the rate at which new BTC enters circulation. Fractal’s mainnet launched in September 2024 using Bitcoin Core code and the same SHA-256 hashing algorithm, and its genesis block carried the same newspaper headline embedded by Satoshi Nakamoto in Bitcoin’s genesis block.
The network has since served as infrastructure for Bitcoin-focused applications. UniSat built its Hexa trading engine on Fractal Bitcoin, citing additional block space and 30-second confirmation times while supporting trading of Bitcoin-based assets.
For miners, the immediate effect of the halving is a 75 percent cut in per-block reward relative to Fractal’s original 25 FB emission, split across the same three mining mechanisms. Whether that translates into proportionally lower miner revenue will depend on transaction fees and demand for block space on the network, the same dynamics that govern miner economics on Bitcoin after each of its own halvings.
Market snapshot at time of writing: BTC 78,995, ETH 2,481.29, SOL 103.79.
Disclaimer: This article is for informational purposes only and does not constitute financial advice.
FIP-102 explicitly not raising total supply is the detail people will skim past. The 6.25 FB set aside for Bitcoin distribution comes out of existing emission, not new mint.
right, and that means current FB holders are not diluted by the mainnet distribution. rare bit of tokenomics discipline in this space.
The no-dilution point cannot be overstated. Nearly every sidechain that announced a mainnet bridge distribution quietly minted new tokens for it
no new mint is why i stopped autocomplaining about the distribution. holders fund their own incentive and that is still cheaper than a bridge token printed out of nothing
block 2,100,000 going through with zero consensus drama, ten clean minutes post activation. pow halvings are never guaranteed till they happen
clean activation is underrated until you remember what a botched one looks like. ill take boring consensus changes over exciting ones every single time
25 to 6.25 FB is rough on small miners. hashrate holding or are we about to see the usual post halving shakeout
the 6.25 FB set aside for distribution on bitcoin mainnet is the more interesting part honestly, FIP-102 without touching total supply
and because the 6.25 FB comes out of existing emission the mainnet distribution is not a stealth airdrop. holders funding their own incentive, weirdly honest
first hour held fine but the shakeout usually shows around week two, when marginal miners actually run the numbers on 6.25 FB against power costs. watching difficulty adjust, not the price chart
week two is exactly the window. merged mining carries the floor but if the permissionless share collapses the 1:1:1 ratio becomes theater on paper
week two plus the first difficulty retarget after the cut is when you get the real answer. if permissionless share holds above the merged mining floor the ratio survives contact with reality
same watchlist. permissionless share above the merged floor by end of month and FIP-102 reads as a masterstroke. below it, its a farm subsidy
week two plus the first retarget is the window. if permissionless blocks start timing out the 1:1:1 split quietly dies and nobody announces it
watching the retarget too but merged mining anchors the floor by design. permissionless share dropping was priced into FIP-102 the moment they kept the 1:1:1 split
hashrate held the first hour from what i saw. real test is whether small miners can cover power costs at 6.25 before the mainnet distribution gives price a reason to hold
check the merged mining share, thats what props hashrate through the 6.25 window. permissionless rigs are always the first to tap out on power costs
merged mining carrying hashrate through a 75% reward cut is the only reason this halving looked calm. watch the permissionless share in two weeks
Nodes and indexing services normal in the first ten minutes, team asking users to report problems directly. calm comms posture for a consensus upgrade day.
6.25 FB against power cost is brutal for solo rigs. merged mining farms absorbing the delta is the quiet consolidation story every single halving runs
solo rigs were marginal at 8.33 per cycle. at 2.08 the only question is how fast they unplug, and the permissionless share number in two weeks tells you whether the 1:1:1 split was ever real
consolidation is the unwritten chapter of every halving doc. small rigs unplug, farms buy the hashrate at a discount, and two quarters later everyone acts surprised the network got more centralized
two halvings in one activation is the wild part. 25 to 6.25 FB in a single upgrade block and difficulty is about to find out what that means for small rigs
agreed, and note the conversion rate is planned 1:1 FB on Fractal to FB on Bitcoin. if FIP-103 actually lands that, holding the sidechain version is the same as holding the mainnet claim. no discount to arb
the math people keep skipping: 6.25 across the 1:1:1 cycle is 2.0833 FB per mechanism, down from 8.33. merged miners on basically free power survive that. index mining might actually feel it first