Number base converter.

Each base writes the same number with a different number of digits: binary (base 2) with 0 and 1, octal (base 8) with 0 to 7, decimal (base 10) with 0 to 9 and hexadecimal (base 16) with 0 to 9 then a to f. 255 is 11111111 in binary, 377 in octal and ff in hex.

Four binary digits make one hex digit, so a byte is exactly two hex characters and a 32-bit word is eight. Colors (#ff5733), memory addresses, hashes and byte dumps are all hex for that reason.

Yes. The arithmetic uses BigInt, so a 128-bit number is converted exactly rather than rounded at 2^53 as plain JavaScript numbers would be.

The way a signed integer is stored: a negative number is written as 2^n plus the number, in the smallest width of 8, 16, 32 or 64 bits that holds it. −1 is ff in 8 bits, ffff in 16. The details pane shows it for any negative input.

Type in any of the four fields and the other three follow. Prefixes (0x, 0b, 0o), spaces, underscores and commas between groups are accepted, as is a leading minus.

The field that doesn't belong to its base is marked and the status says so: a 2 in the binary field, a g in hex. Fix the digit and the conversion resumes.

No. The conversion is a few lines of integer arithmetic that run in your browser; the page makes no request with your numbers.

No. The Number base converter is free and opens without a sign-in, an account or an install.

The Number base converter keeps nothing on a server; only the invoice generator saves its draft, in this browser's localStorage on your device. Nothing else is saved, and nothing is sent to shadcn.io.

Yes. A leading minus is accepted, and the details pane shows the two's complement in the smallest width of 8, 16, 32 or 64 bits that holds the number.

Spaces, underscores and commas between groups are ignored, and the prefixes 0x, 0b and 0o are read.

BigInt, so very large integers convert exactly. The tool works with whole numbers, not fractions.

Closest to the Number base converter: Hex encoder, Binary encoder, Base64 encoder, Calculator. Each opens on its own page, free and in the browser.

The Number base converter is one of 20 in its group. The group's page, /tools/math, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.