Number Base Converter
Convert integers between binary, octal, decimal, hexadecimal, and any base from 2 to 36. BigInt-precise — no rounding, no size limit. Edit any field to update the rest.
About this tool
A positional number system represents a value as a sum of digits times powers of its base (radix). Decimal uses base 10, binary base 2, octal base 8, and hexadecimal base 16. The same integer can be written in any base; this converter shows several at once and updates every field the moment you edit one of them.
Hexadecimal and binary dominate low-level work because they map cleanly to bytes: one hex digit is exactly four bits, so a byte is two hex digits and a 32-bit value is eight. Octal survives mainly in Unix file permissions, where each digit packs the read/write/execute bits of one user class. Decimal is for humans; computers think in base 2.
Because this tool uses BigInt rather than floating-point
math, it is exact for integers of any length — no silent rounding once you
pass 2^53, which is where ordinary JavaScript numbers (and
many naive converters) start losing precision. For arbitrary bases beyond
16, digits continue through the alphabet up to base 36, the largest base
expressible with the digits 0–9 and letters a–z. It does not convert
fractional values; it is built for whole-number radix conversion.
Frequently asked questions
How large a number can this handle?
Arbitrarily large. The converter uses JavaScript BigInt, so there is no 53-bit floating-point limit and no rounding. A 200-digit decimal converts to binary exactly.
Does it support bases other than 2, 8, 10, and 16?
Yes. The bottom row has a base selector for any base from 2 to 36. Bases above 10 use letters a–z as digits (a = 10, b = 11, … z = 35), case-insensitive on input.
Can I convert negative numbers?
Yes — prefix the value with a minus sign. Note that this shows the signed magnitude in each base, not a fixed-width two’s-complement representation. For two’s-complement bit patterns you need to fix a width (8, 16, 32, 64 bits) first.
Why does hexadecimal show lowercase letters?
Output uses lowercase a–f by convention, but you can type either case. Many tools and languages accept both; uppercase is common in color codes and MAC addresses, lowercase in most source code.
Is my input sent anywhere?
No. All conversion is local BigInt arithmetic in your browser. Nothing is transmitted.