Free online checksum calculator. Supports MD5, SHA-1, SHA-256, SHA-512, CRC32 hash algorithms. Enter text or upload files. 100% client-side processing β no data uploaded, safe and reliable.
Multi-AlgorithmFile SupportReal-timeπ Input Text
π Or Upload File
Click to select a file or drag and drop
Supports any file type
π Checksum Results
-----π Verify Checksum
Enter a known checksum to verify it matches
β FAQ
Which algorithms does the checksum calculator support?
It supports MD5, SHA-1, SHA-256, SHA-512, and CRC32. MD5 and SHA-1 are for quick checks, SHA-256 and SHA-512 for security, and CRC32 for file verification.
Is the checksum calculator free?
Yes, completely free. No registration required. All calculations are done locally in your browser β no data is ever uploaded to any server.
Can I calculate checksums for files?
Yes. Drag and drop or click to upload a file. The tool automatically calculates SHA-1, SHA-256, SHA-512, and CRC32 checksums. No file size limit, but large files may take longer.
What are checksums used for?
Checksums are used for: verifying file download integrity, detecting data transfer errors, password storage (SHA-256/SHA-512), digital signature verification, deduplication (identical content produces identical hashes), and software release verification.
What is a checksum error?
A checksum error means the hash calculated from a file does not match the value published by the source, so the file is likely incomplete or corrupted. Re-download the file and compare the SHA-256 value again before using it.
How do I fix a checksum error?
Download the file again over a stable connection, avoid resuming a partial download, then recalculate the hash. If it still mismatches, try another mirror or browser; a repeated mismatch usually means the source file itself is damaged.
About Checksum Calculation
A checksum is a fixed-size digest computed from data using a hash algorithm, used to verify data integrity. This tool supports five mainstream algorithms: MD5 (128-bit, fast, for non-security quick checks), SHA-1 (160-bit, not recommended for security but still useful for verification), SHA-256 (256-bit, high security, widely used for digital signatures and password storage), SHA-512 (512-bit, highest security, for high-security requirements), and CRC32 (32-bit cyclic redundancy check, commonly used for file transfer and archive verification). All calculations are done entirely in your browser locally using the Web Crypto API for SHA algorithms and pure JavaScript for CRC32 β no data is uploaded, ensuring data privacy and security.
What is a checksum error?
A checksum error (also called a checksum mismatch) means the hash your computer calculates from a file does not match the hash published by the source. The file is not necessarily a virus and your disk is not necessarily failing: it simply means the copy you have is not byte-for-byte identical to the original. The usual causes are an interrupted download, a dropped packet in transit, a faulty cable or USB stick, storage corruption, or a file that was changed after it was published.
Why it happens
- Broken or partial downloads: a large ISO, game client or firmware image that lost a few bytes when the connection dropped. Resumed downloads are a common culprit.
- Archive errors: ZIP or RAR files that fail with "CRC failed" or "checksum error in ..." while you extract them.
- Installer failures: Windows reports "The file is corrupt", or a macOS disk image fails its checksum and setup aborts.
- Transfer and copy errors: a file uploaded to cloud storage, sent over FTP, or copied to a USB stick that afterwards refuses to open.
How to verify a file with this tool
- Find the official hash on the download page or in a
SHA256SUMSfile. - Drag the file into the "Or Upload File" box above. It is hashed locally in your browser, so nothing is uploaded anywhere.
- In "Verify Checksum", pick the same algorithm the publisher used and paste their value. A green check means the file is intact; a red cross means a checksum error.
- If it mismatches, download the file again from a stable connection (avoid resuming a partial download) and compare once more.
How to fix a checksum error
Re-download the whole file rather than resuming it, try another mirror or browser, and copy it with a different cable or USB port. If the hash still does not match after a clean download from several sources, the source file itself is probably damaged and you should contact the publisher. Remember that CRC32 only detects accidental transfer errors; use SHA-256 when you need to prove a file has not been tampered with. If the hash matches but the program still fails, the problem is elsewhere: an outdated extractor, the wrong CPU architecture, or missing permissions.