Checksum Calculator (CRC, Adler-32, Fletcher, XOR, Sum)
All common checksums of text or hex in one table: CRC-8, CRC-16, CRC-32, CRC-32C, Adler-32, Fletcher-16/32/64, Internet checksum, XOR/LRC, sum and NMEA.
9 bytes. CRCs follow the reveng catalogue parameters; Fletcher-32 and -64 read the bytes as little-endian words, as in the reference implementations.
| Algorithm | Hex | Decimal | Note |
|---|---|---|---|
| CRC-8/SMBUS | 0x0E | 14 | SMBus PEC |
| CRC-8/MAXIM-DOW | 0xE0 | 224 | 1-Wire |
| CRC-8/AUTOSAR | 0xA8 | 168 | automotive |
| CRC-16/ARC | 0xEE3E | 60,990 | |
| CRC-16/MODBUS | 0x1E34 | 7,732 | sent low byte first |
| CRC-16/CCITT-FALSE | 0xEC0F | 60,431 | |
| CRC-16/XMODEM | 0xF47D | 62,589 | |
| CRC-32 | 0xADAAC02E | 2,913,648,686 | zip, PNG, Ethernet |
| CRC-32C | 0x2D0E3663 | 755,906,147 | Castagnoli, iSCSI |
| Adler-32 | 0x11E60398 | 300,286,872 | zlib |
| Fletcher-16 | 0xEE9A | 61,082 | bytes |
| Fletcher-32 | 0xB7DDA1F8 | 3,084,755,448 | 16-bit little-endian words, zero-padded |
| Fletcher-64 | 0x0F0B0748D2CFCF28 | 32-bit little-endian words, zero-padded | |
| Internet checksum (RFC 1071) | 0x075E | 1,886 | IP, TCP, UDP headers |
| XOR of all bytes (LRC) | 0x45 | 69 | block check character |
| Sum of bytes (8-bit) | 0x97 | 151 | |
| Two’s complement of the sum | 0x69 | 105 | Intel HEX record checksum, Modbus ASCII LRC |
| Sum of bytes (16-bit) | 0x0397 | 919 | |
| Parity of all bits | odd (1) | 35 | 35 one bits |
Checksums detect accidental changes to data: a flipped bit on a serial line, a damaged download, a mistyped record. Different protocols and file formats use different ones, and when you are reverse-engineering a device or a file it helps to see them all at once. This calculator shows the common checksums of text or hex bytes side by side — CRC-8, CRC-16, CRC-32 and CRC-32C, Adler-32, Fletcher-16/32/64, the Internet checksum, XOR/LRC, byte sums and their two’s complement, parity, and NMEA sentence checksums.
How to use this tool
- Paste the data as text or hex bytes.
- Tick the NMEA option for GPS sentences such as $GPGGA,…*47.
- Read the main results, or scan the full table for the value a device or file expects.
- Use the CRC-16 or CRC-32 tools for more variants and custom parameters.
Formula
Adler-32 = B·65536 + A, A = 1 + Σ bytes, B = Σ A (mod 65521) Fletcher-16 = sum2·256 + sum1 (mod 255)
Fletcher-32 and -64 work on 16- and 32-bit little-endian words modulo 65535 and 2³² − 1. The Internet checksum (RFC 1071) is the one’s-complement of the one’s-complement sum of 16-bit big-endian words. LRC is the XOR of all bytes; Intel HEX and Modbus ASCII use the two’s complement of the 8-bit sum, so that all bytes plus the checksum add up to zero.
Example
For Wikipedia, Adler-32 is 0x11E60398 (A = 0x0398, B = 0x11E6), CRC-32 is 0xADAAC02E and the XOR of the bytes is 0x45. For abcde, Fletcher-16 is 0xC8F0, Fletcher-32 0xF04FC729 and Fletcher-64 0xC8C6C527646362C6 — the reference values from the Fletcher checksum article.
Frequently asked questions
Which checksum should I use?
For catching transmission errors a CRC is far stronger than a sum or XOR of the same size. Adler-32 and Fletcher are faster but weaker on short messages. None of them protects against deliberate changes; use a cryptographic hash or HMAC for that.
Why do my Fletcher-32 results differ from another tool?
Implementations disagree on how bytes form 16-bit words. This page uses little-endian words with a zero byte added to odd lengths, which matches the published test vectors.
How do I check an Intel HEX line?
Paste the record’s bytes after the colon without the last byte, as hex. The "two’s complement of the sum" must equal that last byte.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/checksum-calculator/
Cite or embed this tool
kakaoCalc. (2026, November 8). Checksum Calculator (CRC, Adler-32, Fletcher, XOR, Sum). https://kakao.mobile/tools/checksum-calculator/
“Checksum Calculator (CRC, Adler-32, Fletcher, XOR, Sum).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/checksum-calculator/.
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