How does this differ from the Hex to Number Converter?

Hex to Number Converter has no concept of width or sign at all, it just reads the plain magnitude of any-length hex digits. This tool instead requires you to pick a fixed bit width (8/16/32/64) and a signed/unsigned mode, and interprets the exact same hex digits differently depending on those choices, most notably, a value with the top bit set becomes negative when signed mode is on.

What is two's complement?

Two's complement is the standard way computers represent signed integers in binary: for an N-bit signed value, any bit pattern whose top bit is 1 represents a negative number equal to (bit pattern's unsigned value) minus 2^N. It's used because it lets addition and subtraction work identically for positive and negative numbers in hardware.

What happens if my hex value is too big for the chosen width?

It's rejected with an error explaining the maximum value the chosen width can hold; choose a wider bit width (or trim the hex value) if that happens.

Why does the same hex value give a different answer depending on the width?

Because bit width changes which bit is the "sign bit." For example, hex FF is -1 as a signed 8-bit value (all 8 bits set, top bit is the sign bit) but 255 as a signed 32-bit value (only the low 8 bits are set; the actual 32-bit sign bit is 0).

Hex to Integer Converter - Signed/Unsigned Two's Complement Online

Overview

Introduction

The same hex bit pattern can mean two very different numbers depending on whether it's read as signed or unsigned, and how many bits wide the value actually is.

This tool makes that interpretation explicit: pick a bit width and a sign mode, and see exactly what integer that hex pattern represents.

What Is Hex to Integer Converter?

A converter that decodes a hexadecimal bit pattern into a decimal integer under an explicit fixed width (8, 16, 32, or 64 bits) and sign mode (unsigned or two's-complement signed).

Unlike Hex to Number Converter, which treats hex as a plain unsigned magnitude with no width at all, this tool models exactly how a real integer type of a given width and signedness would interpret the same bits.

How Hex to Integer Converter Works

The hex input is validated and parsed into a BigInt, then checked against the chosen width, if the value needs more bits than the width allows, the conversion is rejected.

In unsigned mode the value is returned as-is. In signed mode, if the value is at or above 2^(width-1) (meaning the top bit is set), the width's full modulus (2^width) is subtracted to produce the correct negative two's-complement result.

When To Use Hex to Integer Converter

Use it when you're debugging binary protocols, memory dumps, or register values and need to know what a specific-width signed or unsigned field actually represents.

It's also useful for verifying two's-complement arithmetic by hand, checking your own calculation against an exact reference.

Often used alongside Integer to Hex Converter, Hex to Number Converter and Number to Hex Converter.

Features

Advantages

Models real fixed-width integer semantics exactly, including the width-dependent sign bit.
Supports all four common widths (8/16/32/64-bit) used across most programming languages and protocols.
Uses BigInt throughout, so even 64-bit signed/unsigned extremes convert exactly.

Limitations

Only supports the four standard power-of-two widths (8/16/32/64); arbitrary bit widths (like 12-bit or 24-bit) aren't offered.
Requires the hex value to fit within the chosen width; it won't silently truncate or wrap an oversized value.

Examples

Signed 8-bit interpretation of FF

Input

FF (8-bit, signed)

Output

-1

FF is 255 unsigned; since the top bit of an 8-bit value is set, signed mode subtracts 256 to get -1.

Unsigned 32-bit interpretation of FFFFFFFF

Input

FFFFFFFF (32-bit, unsigned)

Output

4294967295

All 32 bits set, read as unsigned, is exactly 2^32 - 1.

Best Practices & Notes

Best Practices

Always match the bit width to the actual size of the field or variable you're decoding; using the wrong width gives a technically valid but meaningless answer.
When in doubt about a value's signedness, try both modes and see which result makes sense in context.

Developer Notes

The signed conversion computes `value >= (1n << BigInt(width - 1)) ? value - (1n << BigInt(width)) : value` entirely in BigInt arithmetic, avoiding any of the 32-bit truncation that plain JavaScript bitwise operators (`|`, `&`, `>>`) would introduce on wider values.

Hex to Integer Converter Use Cases

Decoding a signed or unsigned field from a binary protocol or file format dump
Checking two's-complement arithmetic homework or interview-prep exercises by hand
Understanding why the same hex value reads differently across different integer types

Common Mistakes

Assuming a hex value's sign is width-independent; the same bits mean a different number at a different width in signed mode.
Choosing unsigned mode when the source data is actually a signed field, silently getting a large positive number instead of the intended negative one.

Tips

If a result looks unexpectedly large and positive, try signed mode, it's a common sign that the top bit was meant to indicate a negative value.
Use Integer to Hex Converter to go the other direction and double-check your understanding of a specific value's bit pattern.

Hex to Integer Converter