Important Notes
Hash calculation time depends on file size. Large files may take longer to process, so keep the page open until the result appears.
About the SHA-1 File Checksum Tool
The SHA-1 File Checksum Tool calculates the SHA-1 hash of a selected file and shows the result as a fixed-length checksum. Use it to compare downloads, verify file copies, or check whether a file has changed unexpectedly.
SHA-1 produces a 160-bit message digest, commonly displayed as a 40-character hexadecimal hash value. After calculating the file's SHA-1 checksum, compare it with the value provided by a software publisher, download page, archive record, or another trusted source.
SHA-1 is a hash function, not encryption. It does not encrypt, decrypt, lock, or hide a file. If you want to create a SHA-1 hash from text, use the separate SHA-1 text hash generator page.
• Features
File SHA-1 Checksum: Select a file and calculate its SHA-1 checksum from the file contents.
Lowercase and Uppercase Output: View the SHA1 hash in lowercase and uppercase formats for easier comparison with different published checksum styles.
Fixed-Length Digest: SHA-1 returns a 160-bit digest, usually shown as a 40-character hexadecimal string.
Checksum Comparison: Compare the generated SHA-1 value with an expected checksum from a trusted source.
File Change Detection: A small change in the file will usually produce a different SHA-1 hash, helping you notice incomplete downloads, transfer errors, or unintended modifications.
• Use Cases
Check Downloaded Files: Compare a downloaded file's SHA-1 checksum with the value shown on a software download page.
Compare File Copies: Generate SHA-1 checksums for file copies to see whether their contents appear to match.
Detect Accidental Changes: Use a SHA-1 checksum to check for changes caused by transfer errors, backups, storage, or sharing.
Work With Legacy Checksums: Some older systems, archives, and download pages still provide SHA-1 values. Use SHA-1 when compatibility is needed, but prefer stronger algorithms for security-sensitive verification.
• Important Security Notes
SHA-1 can be useful for basic file identification, legacy checksum comparison, and accidental-change checks, but it should not be used for modern security-sensitive verification.
Do not rely on SHA-1 for digital signatures, certificates, password storage, or high-trust checks where collision resistance matters. For security-sensitive file verification, use a stronger modern hash algorithm such as SHA-256, SHA-512, or SHA-3 when available.
A matching SHA-1 checksum can help detect accidental corruption or incomplete downloads, but it does not prove that a file is safe, authentic, or free from malicious tampering.