# Number Base Converter

Canonical URL: https://offlineutils.com/number-base-converter
Category: Developer
Published: 2026-07-04
Publisher: offlineutils.com
Runs entirely in the browser; nothing entered into the tool is uploaded.

> A Number Base Converter converts an integer between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36, updating every representation live as you type — computed with BigInt in your browser for arbitrary-size values.

Type a value into any field — binary, octal, decimal, hex, or a custom base you choose (2 to 36) — and every other base updates instantly. It uses BigInt internally, so 64-bit hex constants and huge decimals convert without precision loss, and negative values are supported. Invalid digits for the chosen base are flagged inline. Everything runs locally; nothing is sent anywhere.

## Features

- Binary, octal, decimal, hex, plus any base 2 to 36
- Live two-way conversion across every field
- BigInt precision for 64-bit and larger values
- Negative-number support
- Inline validation of invalid digits
- Runs entirely in your browser — nothing uploaded

## Use cases

- Converting a hex color or memory address to decimal
- Reading a binary bitmask as decimal or hex
- Checking a permission or flag value across bases
- Teaching or learning positional number systems

## How to use it

1. **Pick any field** — Type into binary, octal, decimal, hex, or your custom base.
2. **Read the others** — Every other base updates live as you type.
3. **Copy** — Copy any representation with its copy button.

## When to use it, and when to use something else

- **vs A programmer calculator** — use Number Base Converter when you want all bases visible at once and a shareable web page, no app to open. Use A programmer calculator when you need bitwise operations (AND/OR/shift), which a calculator provides.
- **vs parseInt / toString(radix) in a console** — use Number Base Converter when you want a UI and correct handling of values beyond 2^53. Use parseInt / toString(radix) in a console when you're already scripting and a one-liner is enough.

## Frequently asked questions

### How do I convert binary to decimal?

Type the binary digits into the Binary field; the Decimal field (and every other base) updates instantly. It's fully two-way, so you can start from any base.

### Does it handle very large numbers?

Yes. Conversion uses JavaScript BigInt, so 64-bit hexadecimal values and large decimals convert exactly, with no floating-point rounding.

### What's the maximum base?

36, using digits 0-9 then a-z. You can set any custom base from 2 to 36 in addition to the standard binary, octal, decimal, and hex fields.

### Can it convert negative numbers?

Yes — prefix the value with a minus sign and every base shows the signed value. This tool works with signed integer magnitudes, not two's-complement bit patterns.

## Related tools

- https://offlineutils.com/color-converter
- https://offlineutils.com/hash-generator
- https://offlineutils.com/base64