Hex Converter
Convert hex, decimal, binary, and octal in one place, in your browser. Auto-detects the input base, handles huge numbers. Free, no upload.
About this tool
Paste a number in any common base and see it in all of them at once: decimal, hexadecimal, binary (grouped in 4-bit nibbles), and octal. The input base is auto-detected from a 0x, 0b, or 0o prefix, from hex letters, or defaults to decimal for plain digits.
Conversions use arbitrary-precision arithmetic, so 64-bit IDs, hashes, and other values beyond JavaScript's 2^53 safe-integer limit convert exactly. The report also shows the bit length and, for byte-sized values, the ASCII character.
Common uses
- Check what a hex constant from a stack trace or register dump means in decimal.
- Convert a numeric database ID to hex for a log search, or back.
- See the exact bit pattern of a flags value while debugging a bitmask.
Automate via API
The same conversion is available as a REST endpoint for scripts, pipelines, and backends:
curl -X POST https://payloadly.com/api/v1/tools/hex-converter \ -H "Content-Type: text/plain" \ -H "X-Api-Key: YOUR_API_KEY" \ --data-binary @input.txt
Hex notes
Hexadecimal (base 16) uses the digits 0-9 and a-f, so one hex digit represents exactly four bits. It is the standard notation for memory addresses, byte dumps, color codes, and hashes.
- Hex values are case-insensitive; 0xFF and 0xff are the same number.
- A leading 0x prefix is a convention, not part of the value.
- Each hex digit maps to exactly one 4-bit nibble, which is why hex-binary conversion is mechanical.
Frequently asked questions
Is my data uploaded to a server?
No. This tool runs entirely in your browser using JavaScript, and there are no ads on the page. Nothing you paste or drop here is uploaded, logged, or stored, and you can verify that yourself: open your browser's developer tools and watch the Network tab while you convert (no requests leave the page), or disconnect from the internet after the page loads and keep working.
How is the input base detected?
Prefixes win: 0x means hex, 0b binary, 0o octal. Without a prefix, a value containing the letters a-f is treated as hex, and plain digits are treated as decimal. To force a plain-digit value like 101 to be read as hex or binary, add the prefix (0x101 or 0b101).
Is there a size limit on the numbers?
No practical one. Conversion uses BigInt arithmetic, so 128-bit UUIDs, SHA-256 fragments, and other very large integers convert without the precision loss you get from calculators that go through 64-bit floats.
Is there a size limit or a fee?
The browser tool is free with no signup and comfortably handles files up to tens of megabytes (limited by your device's memory). For automated or bulk processing inside your own scripts and pipelines, use the paid REST API.
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