CRC32 Checksum Generator

About CRC32 checksum generator

CRC32 is a 32-bit cyclic redundancy check that catches accidental changes to data, such as a flipped bit during transfer. This tool follows the IEEE 802.3 variant used by ZIP, gzip and PNG, and gives the checksum of pasted text or a whole file in both hexadecimal and unsigned decimal, so you can compare it with what an archive tool or protocol reports.

How to use it

1. On the Text tab, enter or paste text under Text to checksum.
2. Select Calculate CRC32 to see the result.
3. To checksum a file, open the File tab and select Choose a file. Hashing starts immediately, with a progress bar.
4. Read the Hexadecimal and Decimal boxes. The badge shows whether the source was your text or the file name and size.

The standard CRC-32 check string

123456789

Hexadecimal cbf43926, Decimal 3421780262

When to use it

• Comparing a file's checksum against the CRC column that a ZIP listing prints for each entry.
• Checking that a firmware blob or data dump arrived intact when the specification quotes a CRC-32.
• Validating a home-grown CRC-32 implementation against a known-good reference value.
• Confirming that two copies of a PNG chunk or gzip trailer carry the same checksum.

Questions about CRC32 checksum generator

Can CRC32 be used to prove a file was not tampered with?

No. It is linear and only 32 bits long, so an attacker can adjust a file to reach any target value. It detects noise, not sabotage. Use SHA-256 in the File hash checker when integrity against an attacker matters.

How likely is a collision between two different files?

With 2 to the power 32 possible values, you should expect a coincidental match after roughly 77,000 random files. Any single random change is caught with probability about 99.99999998 percent.

Why are there two output boxes?

Tools disagree about presentation. Archive listings and specifications usually use eight hex digits, while databases and some APIs store the same number as an unsigned decimal. Both are the same 32-bit value.

What is the checksum of empty input?

It is 00000000, because the initial and final XOR masks cancel out. The tool prints all eight digits with leading zeros, so values that begin with zero are never shortened.

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