Solana SOL$81.63-2.4%'s mainnet block compute limit is scheduled to rise from 60 million to 100 million Compute Units when epoch 1009 opens on July 29, 2026, a 66 percent increase delivered by SIMD-0286, a proposal authored by Lucas Bruder of Jito JTO$0.323-1.2% and put forward in May 2025.
The upgrade raises one ceiling. Per the upgrade specification, the per-account cap (the maximum Compute Units any single writable account can consume within one block) holds at 12 million, and the 100 MB limit on block account data size also stays. An account under heavy contention still hits the same wall; a block processing many independent transactions on unrelated accounts can now accommodate substantially more of them without bumping into the block-level limit.
What 11.2% of Blocks at 56M+ CUs Reveals About Demand
The increase is not anticipating a problem that has yet to arrive. Solana's official upgrade page records that since July 22, 2025, when SIMD-0256 raised the block limit from 50 million to 60 million CUs, 11.2 percent of blocks have reached 56 million CU usage or higher. That is a substantial share of blocks already pressing the ceiling. DeFi protocols, order-book DEXs, and applications processing high volumes of parallel transactions on independent accounts are the ones that gain capacity most immediately.
Due to SIMD-0306 which swapped a hard 12M compute unit per acccount cap for a maximum of 40% of the block's compute limit, the per account cap will rise to 40M CU, allowing hot accounts plenty of headroom for multiple updates per slot. For example, a high volume liquidity pool at times of peak volatility would have 66% more capacity for trades in the same slot.
XDP at 70% of Stake Cleared the Activation Threshold
The upgrade proceeds because, per Solana's upgrade specification, over 70 percent of mainnet stake has already enabled XDP, a kernel-bypass networking mode that increases block-propagation headroom. That threshold matters: larger blocks take longer for validators to execute, lengthening replay time and slowing node catchup. The network's assessment is that XDP coverage above 70 percent of stake provides enough margin to absorb that execution cost.
Anza is making XDP the default setting in Agave v4.2, a validator client release also shipping this week. SIMD-0286 has been live on devnet and testnet in advance of the mainnet switch, and validators have had time to prepare.
No Breaking Changes for Developers or Indexers
SIMD-0286 carries no breaking changes. Applications, wallets, and on-chain programs work without modification under the new limit, and no indexing changes are required. The feature gate governing mainnet activation is P1BCUMpAC7V2GRBRiJCNUgpMyWZhoqt3LKo712ePqsz.
Anza CEO Brennan Watt posted ahead of the activation on July 27, describing the upcoming epoch as "raining blockspace."
The second compute-limit increase in a year, SIMD-0286 follows the same logic as SIMD-0256 before it: track demand evidence, confirm network readiness, then expand the ceiling. The 11.2 percent block saturation rate since last July is both the justification for the increase and evidence that demand for the additional headroom already exists.
