Hex to Rust Integer Converter
Convert a hex value into a Rust integer literal — Rust requires an explicit or inferred type suffix like u32 or i64, unlike C's implicit typing.
Built by
Swapnil SanghviFull-Stack Web Developer & WordPress Developer
Swapnil Sanghvi is a full-stack web and WordPress developer, UI designer, and full-time freelancer who builds and maintains Hex Calculator.
Further reading: hex — Stack Overflow
How Rust Represents Hex Literals
A bare 0x-prefixed value is a valid Rust literal, but unlike C, Rust doesn't choose the smallest type that fits automatically — it defaults to i32 unless the context infers otherwise, or you add an explicit type suffix directly to the literal.
Rust Type Suffix Reference
| Suffix | Type | Example |
|---|---|---|
| u8 | unsigned 8-bit | 0xFFu8 |
| i16 | signed 16-bit | 0x7FFFi16 |
| u32 | unsigned 32-bit | 0xFFFFFFFFu32 |
| i64 | signed 64-bit | 0x7FFFFFFFFFFFFFFFi64 |
Where Hex to Rust Integer Actually Comes Up
Defining a Typed Constant
Pasting a hex value from a spec directly into a Rust const declaration, adding the appropriate type suffix to match the intended width and signedness.
const MASK: u32 = 0xFF00FF00;
Initializing a Fixed-Width Field in a Struct
Writing hex literals for struct fields declared with Rust's explicit integer types, relying on the field's declared type rather than a suffix on the literal itself.
let flags: u8 = 0xFF;
Porting a C Constant Into Rust FFI Code
When writing Rust bindings for a C library, converting the C header's hex constants into properly-typed Rust literals for the FFI declarations.
const FLAG_ENABLED: u32 = 0x00000001;
Why Use This Calculator Instead of Doing It by Hand
- Produces a syntactically valid Rust hex literal instantly
- Runs entirely in your browser — nothing you type gets sent anywhere
- Saves manually adding the 0x prefix and fixing letter case
- Reference table alongside the calculator for choosing the right type suffix
Limitations
- Doesn't add a type suffix automatically — add the one matching your intended type (see the reference table above) since Rust requires it be explicit or inferable.
- Doesn't insert Rust's underscore digit separators (like 0xDEAD_BEEF) — the output is a plain, ungrouped literal.
Frequently Asked Questions
Does Rust accept 0x hex literals directly?
Yes — 0xFF is a valid Rust integer literal. Unlike C, Rust literals default to i32 unless the surrounding context infers a different type, or you add an explicit type suffix.
How do I specify the exact type of a Rust hex literal?
Append a type suffix directly to the literal — 0xFFu8, 0xFFFFi32, 0xFFFFFFFFu64 — Rust's suffixes exactly name the type (u8, i16, u32, i64, and so on), unlike C's more generic U/L suffixes.
What happens if a hex literal doesn't fit the inferred type?
Rust's compiler rejects it at compile time with a clear overflow error — unlike C, which may silently truncate, Rust catches a literal that's too large for its (explicit or inferred) type before the program can run.
Can I use underscores in a Rust hex literal?
Yes — Rust allows underscores anywhere in a numeric literal for readability, like 0xDEAD_BEEF, which is equivalent to 0xDEADBEEF.