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An integer written in any supported base.
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Number base converter
Read the same integer in four bases at once, exactly.
Privacy built inYour work stays with you
Binary
11111111
Octal
377
Decimal
255
Hexadecimal
ff
Your work stays private in your browser while you use this tool.
What does number base converter do?
The number base converter reads a whole number written in binary, octal, decimal, or hexadecimal and shows the same value in all four at once. Parsing uses BigInt, so values stay exact above 2^53 where a converter built on ordinary numbers begins rounding.
- Input
- An integer written in any supported base.
- Result
- The same value in binary, octal, decimal, and hexadecimal.
- Price
- Free
- Account
- Not required
How to use number base converter
Choose your settings
Read the same integer in four bases at once, exactly.
Save or copy
The same value in binary, octal, decimal, and hexadecimal.
A practical tip
Values stay exact past 2^53, where a calculator built on floating point starts rounding.
When to use number base converter
Read a hexadecimal colour or memory address as decimal while debugging.
Check a permission bitmask by seeing its binary form beside the decimal value.
Convert a 64-bit identifier without the rounding a floating-point calculator introduces.
Worked example
A concrete number base converter example
- Input
- 0xFFFFFFFFFFFFFFFFFFFF read as hexadecimal
- Result
- 1208925819614629174706175 in decimal, exactly — a Number-based converter reports 1.2089258196146292e+24.
What to expect
How it works
Whitespace and underscores are removed, an optional sign is taken, and a base prefix such as 0x or 0b is stripped. Every remaining digit is checked against the alphabet for the chosen base before parsing, so an invalid character produces a stable error rather than a thrown exception. The value accumulates into a BigInt and is re-rendered in each base; digit grouping is display only and never changes the canonical output.
Know before using
Limits and edge cases
- Only whole numbers are supported. Fractions, exponents, and floating-point notation are rejected rather than truncated silently.
- Input is capped at 4096 digits. The arithmetic would stay exact beyond that, but parsing and re-rendering would stop feeling instant.
Standards and sources
Common questions
Number base converter FAQ
Is number base converter free to use?
Yes. Number base converter is free to use.
Does number base converter keep my work private?
Yes. Your work stays private while you use the tool — nothing you enter is uploaded.
Why does this give a different answer than my calculator for very large numbers?
Most calculators store values as double-precision floating point, which is exact only up to 2^53. Above that they round. This converter uses BigInt, which has no such ceiling, so the digits it prints are the digits of the actual value.
Are 0x and 0b prefixes required?
No. They are accepted and stripped if present, but the base you select is what determines how the digits are read. Output never includes a prefix.