Bitcoin Cash activated its May 2025 network upgrade on May 15, 2025. The release combined two related changes: high-precision integer arithmetic and a resource-based redesign of several CashVM limits.
The authoritative rule changes and activation details are collected in the May 2025 network upgrade specification.
BigInt removed a narrow arithmetic ceiling
Bitcoin-family script historically limited numeric operations to small signed integers even though stack items could contain more data. Contracts that needed large values had to split numbers into pieces or emulate arithmetic through byte operations.
The BigInt proposal extended script-number operations to high-precision integers within the VM's other resource limits. That is useful for:
- fixed-point financial calculations;
- larger counters and identifiers;
- cryptographic or proof-related arithmetic;
- contracts that previously required multi-part number encodings.
High precision does not imply floating-point arithmetic, and it does not make every computation economical. Contract authors still need explicit rounding rules, bounds, and adversarial test cases.
VM limits became more specific
The targeted VM limits proposal replaced several legacy ceilings with limits intended to track actual validation work more closely.
Among the visible effects:
- the old 201-operation bottleneck was removed in favor of operation and hashing budgets;
- maximum stack-item length increased to 10,000 bytes under the new rules;
- signature-check and hashing costs were accounted for more directly;
- larger scripts and proofs became possible without removing all bounds.
The design goal was not "unlimited computation." It was to stop cheap operations from being rejected merely because they crossed a rough historical count while still bounding expensive validation.
What changed for users and builders
Ordinary BCH payments did not need a new address or transaction format. Node operators, exchanges, and infrastructure providers needed compatible software before activation; contract developers gained a larger and more predictable execution envelope.
The upgrade made some contract designs feasible or smaller. It did not audit those contracts, supply reliable price oracles, or eliminate application-level risk.
When evaluating a project that cites the 2025 upgrade, ask which operation was previously blocked, how the new resource budget is calculated, and whether the implementation has independent tests or review.