HesapHanem

CRC32 & Checksum Calculator

Generate CRC and Adler checksums for text or data.

How it is calculated

A checksum condenses text into a short fixed-size value so that accidental changes can be spotted. The tool hashes the exact bytes you type and prints three values in hexadecimal. crc32 is PHP's crc32 algorithm, which is the bzip2 variant of the 32-bit cyclic redundancy check; crc32b is the standard CRC-32 used by ZIP, PNG and Ethernet; adler32 is the Adler-32 sum used by zlib. All are 32 bits (8 hex digits). They detect errors but are not cryptographic: anyone can build different input with the same value. Empty text gives no result, and the checksum covers every character, including spaces and line breaks.

Worked example

Input: hello (5 bytes, no trailing space). The three checksums are crc32 = 3d653119, crc32b = 3610a686 and adler32 = 062c0215. If you compare crc32b with the value published for a file or message, only the standard CRC-32 matches those tools.

Try this example →

Common mistakes

  • Comparing the crc32 line with a ZIP or PNG checksum; those use crc32b, so the values differ.
  • Treating a checksum as a secure hash; it is trivial to craft a collision, so use SHA-256 for integrity against tampering.
  • Adding a trailing space or newline when pasting, which changes every value.
  • Expecting the checksum of a file from its name; the tool hashes the typed text only.
  • Mixing text encodings; the same visible text in UTF-8 and another encoding has different bytes and a different checksum.

About this calculator

This calculator computes CRC-32, CRC-32B, and Adler-32 checksums of any text — short numeric "fingerprints" produced by polynomial division (CRC) or a simple modular sum (Adler-32) that let you detect accidental changes to data. If even one bit of the input changes, the checksum almost always changes too.

Software engineers and network protocol designers use CRC-32 to verify file integrity in formats like ZIP and PNG and in Ethernet frame error-checking, while Adler-32 is used in zlib-compressed data as a faster, lower-overhead alternative.

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Comments (1)

  • Editorial team

    When you compare against another tool, the crc32b line is the one that matches Python's zlib.crc32, but Python prints a decimal number: for hello it shows 907060870, which is 3610a686 in hex. So convert to the same base before deciding two values differ. Adler-32 follows the same rule. Which tool or language are you checking against? Post what it prints for a short test string and what you see here.

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