Number Base Converter
Convert between binary, octal, decimal, hex and any base from 2 to 36 — exact even for huge integers, all in your browser.
That's not a valid number for the selected base.
- Binary base 2
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- Octal base 8
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- Decimal base 10
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- Hexadecimal base 16
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Why convert between bases?
Computers think in binary, programmers often read hexadecimal, and file permissions or legacy systems use octal. Converting a value between these bases makes bit masks, color codes, memory addresses and protocol fields readable — and this tool does it without the precision loss that trips up spreadsheet formulas on large numbers.
How to use it
- Enter a number and tell the tool which base it's written in.
- Read the conversions for binary, octal, decimal and hex, each with a one-click copy.
- Need another base? Set the custom base field to anything from 2 to 36.
Frequently asked questions
Which bases are supported?
It always shows binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16), and there's a custom field for any base from 2 to 36 using digits 0–9 then a–z. You can also choose what base your input is written in.
Can it handle very large numbers?
Yes. The converter uses JavaScript's BigInt, so even numbers with hundreds of digits convert exactly without the rounding errors you'd get from ordinary floating-point math.
Can I paste a 0x or 0b prefix?
Yes. When the input base is set to hexadecimal a leading 0x is accepted, 0o for octal and 0b for binary. Underscores used for digit grouping (like 1_000_000) are ignored too.
Does it support negative numbers and decimals?
Negative integers are supported with a leading minus sign. Fractional values aren't — this tool converts whole numbers between bases, which is the common case for programming and bitwise work.