Number Base Converter

How do I convert between binary, decimal and hex?

What this tool does

Type a value in binary, octal, decimal or hexadecimal and the other three fields update instantly. Optional prefixes (0b, 0o, 0x) are stripped automatically, and BigInt arithmetic handles integers far larger than normal JavaScript numbers allow. Copy decimal with one click when you need a plain integer for docs or code.

Why you need it

Low-level debugging still speaks in bases other than ten. Memory addresses, permission bitmasks, network masks, firmware registers and protocol dumps arrive as hex or binary strings. Color channels and file headers hide numeric values in base 16. Without a fast converter you risk transposing digits, misreading FF as 255 vs 65535 context, or losing precision on 64-bit flags in languages that truncate large integers.

How to use it

1. Click any of the four fields and enter digits for that base.
2. Watch binary, octal, decimal and hex stay synchronized as you type.
3. Paste values with or without 0b / 0o / 0x prefixes.
4. Use Load sample to explore a worked example.
5. Copy decimal for the canonical integer representation.

Practical examples

• Bitmask flags: Convert 0b1010 to decimal 10 to see which permission bits are set.
• Memory dumps: Turn a hex offset like 0x1A3F into decimal for spreadsheet math or array indexing.
• Network math: Express a subnet mask fragment in binary to verify contiguous ones.
• Teaching & interviews: Show how decimal 255 becomes FF in hex and 11111111 in binary.

How it works

Every base is just a different way to write the same integer. Binary (base 2) uses digits 0 and 1 — each position is a power of two. Octal (base 8) groups bits in threes and appears in Unix file permissions. Decimal (base 10) is everyday math. Hexadecimal (base 16) compresses four bits per digit using 0–9 and A–F, which is why dumps and CSS color channels favor it.

When you edit one field, the tool parses valid digits for that radix, converts to a BigInt internally, then renders the equivalent string in each other base. Invalid characters surface as a clear error instead of a silent wrong answer. Because BigInt is used end-to-end, values beyond Number.MAX_SAFE_INTEGER (9,007,199,254,740,991) remain exact — important for 64-bit identifiers and large counters.

Common mistakes

• Invalid hex letters: Only 0–9 and A–F are legal in base 16; G or 8 in octal breaks parsing.
• Leading zeros changing meaning: In some languages 012 is octal; here prefixes disambiguate — use 0o12 when you mean octal.
• Confusing width with value: 000FF and FF are the same number; bit width matters for fixed-size registers, not for numeric equality.
• Float vs integer: This tool handles whole integers only — fractional values belong in a calculator, not a base converter.

FAQ

Related tools

• Hash Generator
• UUID Generator
• Unit Converter
• Percentage Calculator