Convert numbers between binary, octal, decimal and hexadecimal. Edit any field and the others update instantly. Large values are exact, with no rounding.
How to use the Number Base
Type a number into any of the four fields.
The other bases update instantly as you type.
Toggle uppercase hex and copy any value with one click.
This number base converter switches whole numbers between binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16). Every field is editable, so you can type into any base and read the equivalent in the others instantly.
A number base is just how many distinct digits a system uses before it rolls over to the next position. Decimal uses ten (0 to 9), binary uses two (0 and 1), and hexadecimal uses sixteen, adding a to f for the values ten to fifteen, which is why a single hex digit neatly represents four binary bits.
Conversions use arbitrary-precision integers (BigInt), so even very long values stay exact, without the rounding errors that affect ordinary floating-point numbers once they get large.
Bases come up all over low-level work: hexadecimal for colors, bytes and memory addresses, binary for flags and network masks, and octal for Unix file permissions. Reading the same value across bases makes debugging and bit-twiddling much easier.
A leading minus sign is supported for negatives, spaces are ignored so you can group digits for readability, and an option shows hexadecimal in upper or lower case.
It converts integers only; fractional base conversion is a separate problem and is intentionally left out so the results stay exact. Everything runs in your browser.
Frequently asked questions
Binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16). You can edit any of them and the rest follow.
Yes. It uses arbitrary-precision integers (BigInt), so even very long values convert exactly without the rounding errors that affect normal floating-point numbers.
Yes, a leading minus sign is supported. Spaces are ignored, so you can group digits for readability.
No, it converts whole numbers (integers). Fractional base conversion is a separate problem and is intentionally left out to keep results exact.
Each hex digit maps to exactly four binary bits, so a byte is two tidy hex digits. That makes hex a compact, readable stand-in for binary in colors, memory addresses and byte values.
Yes. It runs entirely in your browser, so the numbers you enter are never sent to a server, and it works offline once the page has loaded.
Embed this tool
Add this tool to your own website. Copy the snippet below; it stays up to date automatically.
<iframe src="https://monu.tools/embed/en/number-base-converter" width="100%" height="640" style="border:1px solid #e5e5e5;border-radius:12px;max-width:680px" loading="lazy" title="Monu Tools"></iframe>Related tools
Convert CSV to a Markdown table and Markdown tables back to CSV, both directions.
Decode a JSON Web Token to inspect its header and payload, with human-readable expiry and issue times. Runs entirely in your browser; tokens are never uploaded.
Test a regular expression against your text in real time. See every match highlighted, with capture groups and flags. Runs entirely in your browser.
Build and check cron expressions. Pick a preset or edit the five fields, and see the next run times in your time zone. Runs entirely in your browser.