Number Base Converter

Convert numbers between binary, octal, decimal, and hexadecimal.

Binary (base 2)

Octal (base 8)

Decimal (base 10)

Hexadecimal (base 16)

Arithmetic

Numbers in

First number

Operation

Second number

Every number can be represented in different bases. The base (or radix) tells you how many distinct digits are available before "rolling over" to the next place value. Binary (base 2) uses only 0 and 1 and is the native language of computer hardware. Octal (base 8) uses digits 0–7 and appears in Unix file permissions (e.g., chmod 755). Decimal (base 10) is everyday arithmetic. Hexadecimal (base 16) uses 0–9 and a–f, and is ubiquitous in memory addresses, color codes (#ff5500), and byte-level data.

This tool uses JavaScript's BigInt type for all arithmetic, so it handles arbitrarily large integers without precision loss — no 53-bit limit like Number.

In the arithmetic card, division is whole-number division that rounds toward zero, with the remainder shown beside it — the same rule as / and % in C, Java and JavaScript. Bitwise operations on a negative number act on its two's-complement form.

Link to this tool with values filled in

Everything after the # stays in your browser — it is never sent to a server — so a link like this opens the tool ready to go without the values travelling anywhere but the address bar:

https://crunchify.net/tools/base-converter#value=ff&base=16

Join the settings with &, and percent-encode each value so that spaces, newlines and any #, &, = or % inside one do not break the link. Leave a setting out to accept its default. If a setting is not recognised, the page says so rather than quietly ignoring it.

value (also input, number, n or q) — text, up to 300 characters, required. The number to convert, written in the base named below.
base (also from or radix) — 2, 8, 10 or 16, defaults to 10. Which base the value is written in: binary, octal, decimal or hex.

How do I add or multiply hex or binary numbers?

Use the Arithmetic card: pick the base the numbers are written in, type both, and choose the operation. The answer appears in all four bases at once, so ff + 1 in hex reads 100 in hex and 256 in decimal side by side. Division gives a whole-number quotient and the remainder.

How do I convert binary to decimal?

Multiply each bit by 2 raised to its position (right to left, starting at 0), then sum. Example: 1011 = 1×8 + 0×4 + 1×2 + 1×1 = 11. Or paste the binary number in the Binary field and read the Decimal result.

How do I convert decimal to hexadecimal?

Repeatedly divide by 16, recording remainders (0–9 as digits, 10–15 as a–f), then read the remainders in reverse. Example: 255 ÷ 16 = 15 remainder 15 → FF. Or just type 255 in the Decimal field here.

What is hexadecimal used for?

Hexadecimal (base 16) compactly represents binary data — one hex digit = 4 bits. It is used in memory addresses, color codes (#ff5500), byte values in protocols, and debugging output. Two hex digits represent one byte (0x00–0xFF = 0–255).

What is octal used for?

Octal (base 8) appears mostly in Unix/Linux file permissions. chmod 755 means owner = 7 (rwx), group = 5 (r-x), others = 5 (r-x). Each octal digit represents 3 bits.

Updated October 9, 2026