Number Base Converter Online — Free Tool

Seamlessly convert numbers between Binary, Octal, Decimal, and Hexadecimal representations.

Input base

Input value

Supports optional prefixes: 0x, 0b, 0o.

Decimal

255

Binary

0b11111111

Octal

0o377

Hex

0xFF

Privacy note: All processing happens entirely in your browser. No data is sent to our servers.

About this tool

Binary, octal, decimal, and hexadecimal are common in programming and networking. Convert a number between bases instantly without mental arithmetic.

Enter a value in one base and see equivalents—useful for flags, color hex, and low-level debugging.

Common use cases

Converting hex color channels to decimal
Reading memory addresses and bitmask flags
CS homework and certification study
Debugging protocol fields in packet captures

How to use

Select source base or input format.
Enter the number using valid digits for that base.
Read converted values in all supported bases.
Copy the representation you need for code or docs.

This page is available at /tools/number-base-converter/.

Understanding the result

Invalid digits for a base (e.g. 8 in octal) should error or reject input.
Large integers may lose precision in JavaScript above Number.MAX_SAFE_INTEGER—watch 64-bit values.
Hex often uses 0x prefix in code; tool output may omit prefix for copy-paste flexibility.
Negative numbers need two's complement awareness in fixed-width contexts.

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FAQ

How do I convert binary to decimal?

Each bit is a power of two. The tool automates positional sum for any length.

What is 0x prefix?

C-style hex literal marker. Decimal 255 is 0xFF in hex.

Floating point bases?

This tool targets integers. Fractional base conversion is a separate problem.

Big integers?

Very large values may need BigInt-aware tools beyond standard JS number.