PHP Integer to Hex Converter
Convert a PHP integer to its hexadecimal string form — the exact output PHP's dechex() function returns, including how it handles negative integers.
Built by
Swapnil SanghviFull-Stack Web Developer & WordPress Developer
Swapnil Sanghvi is a full-stack web and WordPress developer, UI designer, and full-time freelancer who builds and maintains Hex Calculator.
Further reading: hex — Stack Overflow
How PHP Converts an Integer to Hex
dechex() converts a decimal integer to its base-16 string form, using lowercase digits with no prefix and no padding by default — combine with str_pad() for fixed-width, zero-padded output.
Where PHP Integer to Hex Actually Comes Up
Generating a Hex Color String
Converting individual RGB integer values to their 2-digit hex form and concatenating them to build a hex color string dynamically.
str_pad(dechex($r), 2, "0", STR_PAD_LEFT)
Formatting an ID or Hash as Hex
Converting a numeric ID or computed hash value to hex for display, logging, or building a compact identifier string.
dechex($id) -> compact hex identifier
Comparing Against a Known Hex Magic Number
Converting a value read from a file to hex to compare it (or log it) against a documented magic number, when debugging a binary file parser.
dechex($bytes) vs. documented magic number
Why Use This Calculator Instead of Doing It by Hand
- Matches the digit output of PHP's dechex() function
- Runs entirely in your browser — nothing you type gets sent anywhere
- Saves manually converting and formatting the output
- Useful for checking expected output before writing test assertions
Limitations
- Adds a 0x prefix and uses uppercase digits — PHP's dechex() returns lowercase digits with no prefix.
- Doesn't zero-pad to a fixed width — combine with str_pad() yourself if you need that.
Frequently Asked Questions
How do I convert an integer to hex in PHP?
Use the built-in dechex() function — dechex(255) returns "ff", lowercase with no prefix.
How do I pad the result to a fixed width?
Combine dechex() with str_pad(), like str_pad(dechex($value), 8, "0", STR_PAD_LEFT), to get a fixed-width, zero-padded hex string.
What does dechex() do with a negative number?
It treats the value as an unsigned integer at PHP's native int width (64-bit on virtually all modern platforms), so a negative number produces a very long hex string rather than a minus sign.
How do I convert a hex string back to an int in PHP?
Use hexdec() — the counterpart to dechex() for parsing a hex string back into an integer (or float, if the value exceeds PHP_INT_MAX).