Number Base Converter

Convert between decimal, hex, binary, octal — or any base from 2 to 36. Powered by BigInt, so it stays exact for values far beyond 64-bit integers.

Binary (base 2)

—

Octal (base 8)

—

Decimal (base 10)

—

Hex (base 16)

—

Base 36

—

Prefixes like 0x, 0b, 0o and trailing underscores in JS literals are accepted. Output is exact for any size — no floating-point rounding.

Walkthrough

How to use it

Choose the base your input is written in.
Type the number — for hex you can include the 0x prefix.
Hit Convert (or just press Enter). All five columns update.
Click Copy on the column you need, or click a column's label to re-convert from that base.

Use cases

When you'd use this

Debugging binary protocols. Decode flag bits from a hex dump into binary to see which bits are set.

Color values. Turn a #RRGGBB color into its decimal channel values, or assemble hex from RGB numbers.

Huge numbers. Converting 128-bit UUIDs or cryptographic values where Number would lose precision — BigInt keeps every digit.

FAQ

Common questions

Why BigInt instead of Number?

JavaScript Numbers are exact only up to 2⁵³. BigInt is arbitrary precision, so converting a 128-bit hash or a 100-digit integer is exact in every digit.

Can it convert negative numbers?

Yes — a leading minus sign is accepted and carried through all bases. Two's-complement bit patterns are not emulated; negative values are shown with a minus sign.

What about decimals and fractions?

This tool handles integers. Values like 3.14 are rejected with a clear message — use a calculator tool for fractional bases.