File Hash Calculator Free Online Tool 2026

Last updated March 22, 2026

What Is a File Hash?

A file hash is a fixed-length string produced by running a file's contents through a cryptographic hash function. The same file always produces the same hash. Any change to the file — even a single bit — produces a completely different hash. This makes hashes ideal for verifying file integrity: if the hash matches the expected value, the file is intact and unmodified.

Common Use Cases

• Download verification: Software publishers post SHA-256 hashes alongside downloads. You compute the hash of your downloaded file and compare it to the published value.
• Deduplication: Find duplicate files by comparing hashes instead of byte-by-byte comparison.
• Version control: Git uses SHA-1 (transitioning to SHA-256) to identify every commit, tree, and blob object.
• Digital signatures: Sign the hash of a document rather than the document itself — much faster for large files.
• Forensics: Law enforcement uses MD5/SHA-1 hashes to prove a file hasn't been tampered with since collection.

Computing File Hashes

# Linux / macOS
sha256sum file.iso
md5sum file.iso
sha1sum file.iso

# macOS (shasum)
shasum -a 256 file.iso
shasum -a 512 file.iso

# Windows PowerShell
Get-FileHash file.iso -Algorithm SHA256
Get-FileHash file.iso -Algorithm MD5

# Python
import hashlib

def file_hash(path, algorithm='sha256'):
    h = hashlib.new(algorithm)
    with open(path, 'rb') as f:
        for chunk in iter(lambda: f.read(65536), b''):
            h.update(chunk)
    return h.hexdigest()

print(file_hash('ubuntu.iso'))  # sha256 by default

Which Algorithm to Use?