Number Base Converter

How to use Number Base Converter

Three simple steps, with your content kept on your device.

Built for useful work

Fast, focused, and made to be clear on every screen.

What is a number base converter

A number base converter changes a value written in one positional numeral system into its equivalent in another. Instead of doing the arithmetic by hand, you type the digits and the tool returns the matching value in the target base.

Every base works on the same principle: each digit position represents a power of the base. In binary (base 2) the positions are powers of two, in octal (base 8) powers of eight, and in hexadecimal (base 16) powers of sixteen. A base conversion calculator simply applies those weights for you.

How to convert between bases

Type a number such as 255, choose the source base on the left, and pick the target base on the right. The converted value appears instantly along with the decimal form and digit counts for both the integer and fractional parts.

The converter works in every direction: decimal to binary, hex to octal, binary to decimal, and every other pair. Because the conversion happens locally, you can run dozens of quick checks without any page reload or network request.

Binary, octal, decimal, and hexadecimal

These four bases cover the systems you meet most often in computing and programming. Binary uses only 0 and 1 and mirrors how machines store data. Octal groups bits in threes and was common in older systems, while hexadecimal groups bits in fours and is the standard shorthand for memory addresses and color codes.

Hexadecimal uses the digits 0-9 followed by the letters a-f, so a byte like 11111111 is written as ff. Being able to switch between binary octal decimal hexadecimal notation quickly is a daily convenience for developers, students, and anyone debugging low-level code.

Converting fractional values

Fractions convert digit by digit: 0.5 in decimal becomes 0.1 in binary, and 0.625 in decimal becomes 0.101 in binary. The tool keeps up to 16 fractional places so common values stay accurate without endless repeating digits.

Some fractions never terminate in another base, which is why the result shows a limited number of fraction digits. That limit is stated clearly so you know exactly how precise the output is.

A common example: 0.1 in decimal repeats forever in binary, just as 1/3 repeats forever in decimal. When a conversion reaches the digit limit, the trailing value is the closest representable result, which is the same behavior you would expect from any serious converter.

Large numbers and BigInt

The integer part is converted with BigInt arithmetic, so values far beyond the normal JavaScript number range stay exact. A 40-digit decimal or a very long binary string converts without rounding.

A safety limit on input length protects the browser from extreme pastes, and the error message names the limit when you hit it. The rest of the time, very large values convert exactly and immediately.

This makes the tool useful beyond casual checks: converting a 64-bit hash fragment, a subnet mask, or a memory address from decimal to hex takes a single paste, and the BigInt path keeps every digit faithful to the source.

Related number and text tools

Base conversion pairs well with the rest of Valestiom's number toolkit. The Number Formatter adds locale-aware separators, currency, and compact notation to converted values, and the Number to Words converter spells a value out in English.

When you are preparing data, the Line Sorter and Slug Generator tidy up the surrounding text, and the Unit Converter handles measurements such as length, weight, and temperature that base conversion does not cover.

Because everything runs locally, the converter is also a handy study tool: enter a value, check the decimal readout, and verify your own hand conversion before you submit an assignment or ship a code review.

Frequently asked questions