Zcash NU7 Upgrade Activates on Mainnet Shortening Block Time to 25 Seconds

The Zcash NU7 upgrade activated on mainnet at block 3,543,405 around 02:34 UTC on November 6, 2026. The changes shorten the target block interval, adjust issuance to preserve the overall supply schedule, and redirect a portion of transaction fees into a reserve.

Zcash NU7 Upgrade Implementation Details

ZIP 218 sets the new target block time at 25 seconds. Block subsidy per block fell by roughly two-thirds to keep daily ZEC issuance near previous levels. The interval between halvings lengthened from one halving cycle to three cycles so the 21 million ZEC cap remains unchanged. Miners now receive 40 percent of transaction fees while 60 percent move to a public reserve under the Network Sustainability Mechanism.

Version 4 transactions were invalidated under ZIP 2003, leaving approximately 12,224 ZEC in the Sprout shielded pool unspendable. Shielded action limits per block were added to control validation load. The difficulty adjustment window expanded from 17 to 102 blocks. Early post-activation blocks averaged 39 seconds while the network adjusted toward the 25-second target.

Testnet measurements recorded orphan rates of about 3.43 percent under load compared with 1.57 percent before the change. Private payment throughput rose from roughly three to more than six transactions per second for simple Orchard transfers. Daily wallet sync data requirements dropped from 271 MB to 169 MB.

Network Sustainability Mechanism and Supply Context

The Network Sustainability Mechanism removes 60 percent of each block’s transaction fees from circulation. The reserve will support security once subsidies decline further, with reissuance scheduled to begin at block 8,939,664 around early 2031. Initial estimates place annual reserve accumulation near 210 ZEC from current fee levels.

NU7 followed testnet activation at block 4,465,026 on October 4, 2026. The Zcash Foundation, Zakura, Zebra teams, and Shielded Labs coordinated deployment under ZIP 259. No new transaction formats were introduced, and Sapling and Orchard pools remain unaffected for users.

Difficulty adjustment continues after activation. Explorers including ZecStats and Blockchair provide real-time monitoring. Node operators have applied the required software updates without widespread service interruptions reported in the first hours.

Early Performance and Next Steps

Orphan rates stayed within manageable ranges during initial stress testing. Faster blocks increase confirmation speed for shielded transactions while the fee reserve begins modest accumulation. Wallet developers confirmed compatibility for the majority of users holding funds in current shielded pools.

Monitoring will focus on the ongoing convergence of block intervals to the 25-second target and reserve growth through 2031. No immediate changes to the overall monetary policy or total supply cap have occurred.