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CRC32 Calculator

Compute a CRC-32 checksum in hex, decimal and signed form.

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Quick Tool Overview

The CRC32 Calculator computes the IEEE 802.3 checksum — the one zip, gzip and PNG use — and reports it as hexadecimal, unsigned decimal and the signed 32-bit integer that languages without an unsigned type produce.

What it does
Computes a CRC-32 checksum
You give it
Any text
You get back
The checksum in hex, unsigned and signed form
Best for
Comparing checksums between tools and languages
Developer Tools Free, unlimited use No sign-up Runs in your browser

About the CRC32 Calculator

CRC-32 is an error-detecting code, not a hash. It uses the IEEE 802.3 polynomial and produces a 32-bit value — the same one zip archives, gzip streams and PNG chunks carry to prove their contents arrived intact.

The result is shown three ways because different systems report it differently: hexadecimal, unsigned decimal, and the signed 32-bit integer that languages with no unsigned type produce. That last one is why a checksum can look negative in Java or older PHP while a command-line tool reports a large positive number — they are the same 32 bits read differently, which this makes obvious rather than mysterious.

Key features of the CRC32 Calculator

All three representations

Hexadecimal, unsigned decimal and signed 32-bit, which is why the same checksum can look negative in Java and positive on the command line.

The right polynomial

Uses 0xEDB88320, the IEEE 802.3 variant, which is what zip, gzip, PNG and Ethernet mean by CRC-32.

Comparison built in

Paste an expected value in any of the three forms and the tool tells you whether it matches.

Clear about what it proves

CRC-32 catches accidental corruption and nothing else — a deliberate collision is trivial, and the page says so.

Instant on large input

A table-driven implementation, so even a long document is checksummed as you type.

How to use the CRC32 Calculator

  1. 1

    Paste your text

    The checksum updates as you type.

  2. 2

    Read all three forms

    Hexadecimal, unsigned decimal and signed 32-bit, so it matches whatever you are comparing against.

  3. 3

    Compare a value

    Paste an expected checksum and the tool tells you whether it matches, in any of the three forms.

  4. 4

    Copy what you need

    Click any of the three representations to copy it.

Frequently asked questions

Not a cryptographic one. It detects accidental corruption very well and is extremely fast, but it is trivial to construct a different input with the same checksum, so it proves nothing about intent.

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