CRC32 Checksum Calculator
Free CRC32 checksum calculator: get the CRC-32 of any text or file as 8 hex digits and a decimal number, using the same polynomial as zip, gzip and PNG files.
How to use CRC32 Checksum
- 1Type or paste text, or choose “Hash a file” to checksum its bytes.
- 2Copy the 8-digit hex CRC-32, or read the decimal and signed values under it.
- 3Paste a known CRC-32 into “Compare with” to confirm it matches.
What makes it better
- CRC-32 as 8 hex digits plus unsigned decimal and signed 32-bit values
- Same variant as zip, gzip, PNG and Ethernet (check value cbf43926)
- File checksums in chunks with a progress bar
- Compare with a CRC-32 from an archive listing or a download page
- MD5, SHA-1 and SHA-2 hashes are available under “More algorithms”
About CRC32 Checksum
CRC32 Checksum Calculator computes the 32-bit cyclic redundancy check (IEEE 802.3, polynomial 0xEDB88320) of your text or file. You get the 8-digit hex value and the decimal number, and files are processed in chunks on your device. CRC-32 is built to notice accidental damage quickly; it is not a security feature.
Common uses
- Check a file extracted from a zip against the CRC-32 shown in the archive listing.
- Confirm a PNG chunk or downloaded asset was not damaged in transit.
- Reproduce the checksum a firmware or protocol document says a message should have.
- Spot an accidental change in a large data file without computing a heavier hash.
Example
Input
123456789
Result
cbf43926
Good to know
- CRC-32 detects accidental errors such as flipped bits and truncated files. It offers no protection against tampering, because anyone can alter a file and adjust it so the CRC stays the same.
- With only 32 bits there are about four billion possible values, so unrelated files can share a CRC-32 by chance. Use SHA-256 when you need to identify a file with confidence.
- This is the common IEEE CRC-32 (reflected, init 0xFFFFFFFF, final XOR 0xFFFFFFFF). Other variants such as CRC-32C or CRC-32/BZIP2 give different values for the same input.
CRC32 Checksum FAQ
What is a CRC32 checksum?
A CRC32 is a 32-bit number computed from data by polynomial division. Storing it next to the data lets a receiver recompute it and notice if bits were changed, which is why formats like zip and PNG include one.
Is CRC32 a secure hash?
No. It is designed for error detection, not for resisting an attacker, and a modified file can be crafted to keep the same CRC-32. Choose SHA-256 for integrity you need to trust.
Why is the CRC-32 of “123456789” always cbf43926?
That string is the standard test input for CRC algorithms, and cbf43926 is the published check value for the IEEE CRC-32. If your result matches, your tool uses the same parameters as zip and PNG.
Why does my CRC-32 differ from the one in another program?
Check the variant first: CRC-32C (Castagnoli), CRC-32/BZIP2 and others use different polynomials or bit order. Also compare identical bytes, since line endings and encodings change the checksum.
How is the decimal value related to the hex value?
They are the same 32-bit number written differently. Hex cbf43926 is 3421780262 as an unsigned decimal. Languages with signed integers may print the same bits as a negative number, shown here as the signed value.