How large a number can I convert?

Arbitrary precision via BigInt, so very large integers are supported.

Can I convert negative numbers?

The custom base output preserves a leading minus sign for negative values.

What bases are supported for the custom field?

Any base from 2 to 36 using digits 0-9 and letters a-z.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

Number Base Converter

Convert numbers between binary, octal, decimal, hex, and custom bases.

Support

Works Offline

Privacy First

No Login

No API

Binary (base 2)

Binary

Octal (base 8)

Octal

Decimal (base 10)

Decimal

Hexadecimal (base 16)

Hexadecimal

Custom base (2–36)

Base

Value

About the Number Base Converter

Live-sync a number across binary, octal, decimal, and hexadecimal, plus any custom base from 2 to 36, using arbitrary-precision BigInt math so large numbers stay accurate.

Examples

Decimal 42

Output

0b101010 / 0x2a

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser