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CRC32 Checksum Calculator

Compute the IEEE 802.3 CRC-32 of text or a file, as 8-digit hex and an unsigned decimal integer.

Source

Checksummed live as you type. Nothing leaves your browser.

Hex format

Checksum
CRC-32 (hex)
00000000
Decimal (unsigned)
0

0 bytes · IEEE 802.3 (CRC-32/ISO-HDLC)

How to calculate a CRC-32 checksum online

  1. Choose text or a file

    Pick Text to checksum what you type or paste, or File to drop, browse, or paste a document, image, or archive.

  2. Read the checksum

    The CRC-32 appears as an 8-digit hexadecimal value and an unsigned decimal integer the moment there is input, with no button to press.

  3. Adjust the format

    Toggle uppercase letters or a 0x prefix on the hexadecimal value to match the convention your tool or spec expects.

  4. Copy the value

    Use the copy button beside either the hex or decimal result, or the full-width button to grab the checksum in one tap.

Why use this tool

Text or any file

Switch between typing text and dropping a file. A file is read over its raw bytes, so the checksum matches what a build tool or archive reports for that exact file.

Hex and decimal at once

Every input produces both the standard 8-digit hexadecimal checksum and the equivalent unsigned decimal integer, so you never convert between the two by hand.

Standard IEEE 802.3 CRC-32

The checksum uses the same polynomial as gzip, zip, PNG, and Ethernet, so results line up with the CRC-32 those formats store internally.

Handles large files

Big files are read in pieces so the tab stays responsive, and an empty input is treated as the valid checksum 0x00000000.

Uppercase and prefix options

Flip the hexadecimal value to uppercase or add a 0x prefix to match whatever a config file, checksum list, or firmware tool expects.

Nothing leaves your browser

The text and files you check stay on your device. Nothing is uploaded, logged, or kept after you close the tab.

About this tool

This CRC-32 calculator computes the standard IEEE 802.3 checksum, sometimes called CRC-32/ISO-HDLC, for either text you type or a file you drop in. Text is measured over its UTF-8 bytes and a file is read over its raw bytes, so the value matches the CRC-32 that formats like gzip, zip, and PNG store internally. The result appears the moment there is input, as an 8-digit hexadecimal value and as an unsigned decimal integer, with no button to press.

CRC-32 is a fast integrity check, not a security hash. It is built to catch accidental corruption, a flipped bit in a download, a truncated file, or a bad copy, rather than to resist a deliberate attacker. Because it is short and quick, it is ideal for verifying archives, comparing two files, seeding a cache key, or matching the checksum a build system prints. If you need a value that resists tampering, reach for the hash generator or a dedicated SHA-256 hash generator instead.

Everything runs on your device, so the text, keys, or files you check never travel anywhere. Empty input is treated as a valid checksum of 0x00000000, large files are processed in pieces so the page stays responsive, and the final value is always clamped to a 32-bit unsigned integer. Use the uppercase and 0x-prefix toggles to match a specific convention, and copy the hexadecimal or decimal form with one tap. To turn the hex result into another base, see the number base converter.

Frequently asked questions

What is a CRC-32 checksum?
CRC-32 is a 32-bit cyclic redundancy check: a short fingerprint of some data used to detect accidental changes. This tool uses the standard IEEE 802.3 polynomial (0xEDB88320), the same one gzip, zip, and PNG use, and shows the result in both hexadecimal and decimal.
Can I calculate the CRC-32 of a file?
Yes. Switch the source to File, then drop, browse, or paste a file of any type. It is read over its raw bytes, so the checksum matches the CRC-32 an archive or build tool would report for that exact file.
Why are the hex and decimal values different lengths?
They are two ways of writing the same 32-bit number. The hexadecimal form is always 8 digits, padded with leading zeros, while the unsigned decimal form ranges from 0 up to 4,294,967,295. Both describe the identical checksum.
Is CRC-32 secure enough for passwords or signatures?
No. CRC-32 only detects accidental corruption and is trivial to forge on purpose, so it is unsuitable for passwords, signatures, or tamper protection. For those, use a cryptographic hash like SHA-256 instead.
Is my text or file uploaded anywhere?
No. The checksum is calculated entirely in your browser. The text and files you check never leave your device, are never sent to a server, and are not stored or logged.
What checksum does empty input give?
An empty input returns 0x00000000, which is the correct CRC-32 of zero bytes. As soon as you add any text or choose a file, the value updates to that input’s checksum.

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