Crypto · 17 September, 2026 · 3 min read
Zcash Developers Target Nov. 5 NU7 Mainnet Upgrade With 25-Second Blocks
NU7 lowers block time to 25 seconds while preserving Bitcoin-style halvings. Testnet activation on Oct. 6; mainnet target is Nov. 5, 2026.
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NU7 Timeline and Block Speed
Zcash developers have targeted Nov. 5 for the NU7 mainnet upgrade, with testnet activation planned for Oct. 6 and a final decision on the mainnet start date scheduled for Oct. 20.
“Zcash developers are targeting Nov. 5 for the NU7 upgrade, which would cut block times to 25 seconds from 75 seconds”
The NU7 package centers on cutting Zcash’s target block time from 75 seconds to 25 seconds, with the upgrade also set to disable version 4 transactions and deploy the Network Sustainability Mechanism.
Coinholder voting closed Sept. 14, with official forum tallies showing 98.9% of participating ZEC backed keeping Bitcoin-style halvings while also supporting the faster-block proposal.
Sean Bowe’s statement describes a shared understanding among the Zcash Foundation, Project Tachyon, Valar Group, ZODL, Shielded Labs, and all engineers about the scope and timeline of deliverables, which the article says will be ready by Sept. 30.
The NU7 plan also includes a Network Sustainability Mechanism schedule under which at least 60% of transaction fees would be burned and re-injected into the circulating supply around February 2031.
ZIP 218 Limits and Testnet
A major NU7 proposal described as ZIP 218 would lower Zcash’s target block time from 75 seconds to 25 seconds while continuing to issue the same number of ZEC▲$1,136.20each day by reducing the subsidy paid per block.
The proposal defines maximum actions to limit the cost of running the network per block, including that a block may not contain more than 330 total actions across all pools and at most 330 Orchard actions, 300 Sapling inputs and outputs combined, and 25 Sprout JoinSplits.
The expected throughput in Orchard for standard two-action transactions is given as 2.9 transactions per second, with testing also cited as showing a stale block rate of around 3.26% when inter-block spacing was 25 seconds.
Testing from a global region with 99 Zebra nodes using 2 MB blocks is described as producing a stale-rate of 4.86% and fork-rate of 0.37%.
The article says developers will deploy NU7 to a testnet and observe its behavior over a two-week period before setting a new mainnet activation height, with code completion targeted for Sept. 30.
What Changes for Users
NU7 is expected to speed up private payments by up to three times, with the block-time reduction to 25 seconds framed as a way to shorten confirmation times for payments, exchange deposits, and cross-chain operations.
“reducing the block time to 25 seconds, a significant reduction from the current 150 seconds”
The upgrade is also described as reserving at least 60% of transaction fees to complement mining rewards starting in 2031, while preserving Zcash’s commitment to privacy and decentralization.
Coinholder support for the monetary policy is reported as 98.9% backing the existing halving schedule, while the same coverage says 96.6% chose February 2031 as the starting point for returning collected fees to miners.
The NU7 plan would disable older transaction formats, including deactivating version 4 transactions so it would not be possible to spend from the legacy Sprout pool with version 5 transactions, while the remaining balance in the Sprout pool would not move to the orphaned state.
While wallets are said to be not expected to require significant changes, the sources warn that full nodes, indexers, and block explorer services may need updates as NU7 integrates the Network Sustainability Mechanism and changes consensus rules.