# Proposal: Decoupling Int Width from Pointer Size

**URL:** <https://forum.modular.com/t/proposal-decoupling-int-width-from-pointer-size/2558>\
**Category:** Language Design\
**Created:** [December 28, 2025, 4:32pm UTC](https://forum.modular.com/t/proposal-decoupling-int-width-from-pointer-size/2558 "2025-12-28T16:32:12Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![leb-kuchen](https://avatars.discourse-cdn.com/v4/letter/l/a183cd/32.png) [@leb-kuchen](https://forum.modular.com/u/leb-kuchen)\
**Post date:** [December 28, 2025, 4:32pm UTC](https://forum.modular.com/t/proposal-decoupling-int-width-from-pointer-size/2558/1 "2025-12-28T16:32:12Z")

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# Proposal: Decoupling Int Width from Pointer Size

**Summary:** Define `Int` as a platform-dependent type with a guaranteed minimum width of 64 bits, distinct from the system’s pointer width.

### Motivation

- **Default Robustness:** As the default type for literals and arguments, `Int` requires a generous minimum width to ensure portability and prevent overflow across platforms.
- **Divergent Requirements:** The assumption that `size_of(Pointer) == size_of(Integer)` is a legacy constraint. Future architectural needs (e.g., 128-bit contexts) may not align linearly for both types.
- **The 32-bit Indexing Limit:** Current 32-bit constraints prevent indexing collections larger than ~2GB, a critical limitation for Wasm32 targets. Adopting a 64-bit standard eliminates this bottleneck entirely.

### Performance & Implementation

- **64-bit Systems:** Zero runtime overhead; maps directly to native registers.
- **32-bit Systems (inc. Wasm):** Minimal impact. Modern 32-bit architectures and Wasm32 utilize efficient hardware support for 64-bit arithmetic, adhering to Mojo’s strict performance mandates while significantly improving ergonomics and safety.