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crate documentation minimum rustc 1.31 build status

Big integer types for Rust, BigInt and BigUint.


Add this to your Cargo.toml:

num-bigint = "0.4"


The std crate feature is enabled by default, and is mandatory before Rust 1.36 and the stabilized alloc crate. If you depend on num-bigint with default-features = false, you must manually enable the std feature yourself if your compiler is not new enough.

Random Generation

num-bigint supports the generation of random big integers when the rand feature is enabled. To enable it include rand as

rand = "0.8"
num-bigint = { version = "0.4", features = ["rand"] }

Note that you must use the version of rand that num-bigint is compatible with: 0.8.


Release notes are available in


The num-bigint crate is tested for rustc 1.31 and greater.


While num-bigint strives for good performance in pure Rust code, other crates may offer better performance with different trade-offs. The following table offers a brief comparison to a few alternatives.

Crate License Min rustc Implementation Features
num-bigint MIT/Apache-2.0 1.31 pure rust dynamic width, number theoretical functions
awint MIT/Apache-2.0 1.66 pure rust fixed width, heap or stack, concatenation macros
bnum MIT/Apache-2.0 1.61 pure rust fixed width, parity with Rust primitives including floats
crypto-bigint MIT/Apache-2.0 1.57 pure rust fixed width, stack only
ibig MIT/Apache-2.0 1.49 pure rust dynamic width, number theoretical functions
rug LGPL-3.0+ 1.65 bundles GMP via gmp-mpfr-sys all the features of GMP, MPFR, and MPC


Licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.