CRC32 Calculator
Get the CRC-32 checksum of text or files, plus CRC-32C, Adler-32 and two common CRC-16 variants, and check it against the value you expect. Files of any size are read in chunks on your device.
CRC32 Calculator
Files are read by your browser and never uploaded. Nothing leaves your device.
Runs in your browser. Files and audio never leave your device.
Scratchpad auto-saved
How it works — in four simple steps
No signup and nothing to install — it all runs in your browser.
Type text or drop files
Text updates as you type.
Pick the format
Hex or decimal.
Compare
Paste the expected checksum.
Read the result
Matches are highlighted.
CRCs catch accidents, not attacks. Use SHA-256 to check a download hasn't been tampered with.
Features
Five checksums
CRC-32, CRC-32C, Adler-32, CRC-16/ARC and CRC-16/CCITT-FALSE.
Text and files
Live text checksums; files of any size, read in chunks.
Compare
Paste an expected value to highlight matches.
Output formats
Hex (upper/lower), 0x-prefixed or decimal.
Verified
Gives the standard check values for 123456789 (CBF43926, E3069283, BB3D, 29B1).
Private
Files stay on your device.
About the CRC32 Calculator
A cyclic redundancy check is a fast checksum for catching accidental corruption. CRC-32 (the ISO-HDLC variant, polynomial 0x04C11DB7, reflected) is the one in ZIP archives, PNG chunks, gzip and Ethernet frames. The standard check value, the CRC-32 of the text 123456789, is CBF43926, which is the default example above. CRC-32C (Castagnoli) detects errors better and has hardware support in modern CPUs, which is why iSCSI, ext4, Btrfs and SCTP use it. Adler-32 is zlib's faster, weaker checksum.
Type text to see every checksum update live (calculated on its UTF-8 bytes), or drop files to checksum them. Files are read in 4 MB chunks, so even multi-gigabyte files work without loading into memory. Paste an expected value and matching results light up. The format menu switches between upper- and lower-case hex, 0x-prefixed hex and decimal, since tools disagree on how to print them.
CRCs are for detecting accidental changes such as transmission errors and bad sectors. They aren't secure: anyone can deliberately craft a file with a chosen CRC. To check a download hasn't been tampered with, compare a SHA-256 hash instead, using the hash generator.