Number Base Converter

Convert between binary, octal, decimal, hexadecimal and any base from 2 to 36 — instantly, BigInt-accurate for huge integers, with one-click copy.

Popular Conversions

Dedicated pages for the most-searched base conversions, each with a quick converter and a reference table.

binary to decimal · decimal to binary · hex to decimal · decimal to hex · binary to hex · hex to binary · octal to decimal · decimal to octal · octal to binary · binary to octal · hex to octal · octal to hex

Unit conversions

kg to pounds · pounds to kg · kg to stone · stone to kg · grams to ounces · ounces to grams · cm to inches · inches to cm · mm to inches · inches to mm · meters to feet · feet to meters · feet to inches · inches to feet · km to miles · miles to km · Celsius to Fahrenheit · Fahrenheit to Celsius · liters to gallons · gallons to liters · mL to fl oz · fl oz to mL · mph to km/h · km/h to mph

Converting money? Use the Currency Converter for live exchange rates.

How to Convert Between Number Bases

Three steps, all in your browser.

1

Type the number

Enter your value — spaces, commas and underscores are ignored, and an optional leading minus is allowed. Bases above 10 use letters (A–F for hex, on up to Z for base 36), in upper or lower case.

2

Pick the source base

Tap Binary, Octal, Decimal or Hexadecimal, or type any base from 2 to 36. Each digit is checked against that base, so an invalid character like "2" in binary is flagged instead of silently mis-converting. Spelling the number out in words instead? Use the Numbers to Words Converter.

3

Read and copy

Binary, octal, decimal and uppercase hexadecimal update live, plus any target base you choose. Every value is computed with BigInt, so huge integers stay exact. Hit Copy on any row — nothing is uploaded, it all happens on your device.

Frequently Asked Questions

How do I convert binary to decimal?
Set the source base to Binary (base 2) and type your bits, for example 11111111. The decimal value appears instantly in the Decimal row — 11111111 is 255. Under the hood each binary digit is a power of two: reading 11111111 from the right, that is 1+2+4+8+16+32+64+128 = 255. You can also click Decimal, Octal or Hex as the source base if you are converting the other direction, and the converter keeps all four outputs — binary, octal, decimal and hexadecimal — in sync as you type.
What is hexadecimal used for?
Hexadecimal (base 16) uses the digits 0–9 then A–F, so one hex digit represents exactly four binary bits and two hex digits represent one byte. That compactness makes it the standard notation for memory addresses, byte values, color codes like #4F46E5, MAC addresses and hashes. This tool outputs hex in uppercase (FF rather than ff) and accepts hex input in either case, so you can paste a value straight from a debugger, a CSS color or a hex dump and read its decimal or binary equivalent.
What bases does this converter support?
This converter handles binary, octal, decimal and hexadecimal all at once, and it also takes any source base from 2 to 36 and shows the result in any target base from 2 to 36. Bases above 10 use letters as extra digits: A–F for bases up to 16 and on up to Z for base 36. Digits are validated against the base you pick — for example the digit 2 is rejected in binary and G is rejected in hexadecimal — and a clear inline message tells you which character was invalid.
Does it handle very large numbers?
Yes — very large numbers convert exactly. The conversion is built on JavaScript BigInt, so it works on integers far beyond the 253 limit of ordinary floating-point numbers — you can convert values like 270 or a 100-digit number without any rounding or loss of precision. Because every base is computed from the same exact integer, the binary, octal, decimal and hexadecimal outputs always agree to the last digit.
Is my data private?
Yes — the number base converter keeps your data private. It runs entirely in your browser with JavaScript — the numbers you type are never uploaded, logged or stored, there is no account or sign-up, and the tool keeps working offline once the page has loaded. Everything, including the copy buttons, happens on your own device.

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