MD5 vs SHA-256
Which hash algorithm should you actually use?
The short answer
Use SHA-256 unless you have a specific reason not to. MD5 is faster and shorter, but it has been breakable since 2004, so it cannot tell you whether a file was deliberately tampered with. MD5 is still fine for one job: spotting accidental corruption, such as a truncated download or a bad disk copy.
Side by side
| MD5 | SHA-256 | |
|---|---|---|
| Digest length | 128 bits (32 hex chars) | 256 bits (64 hex chars) |
| Published | 1991 | 2001 |
| Family | MD | SHA-2 |
| Collision resistance | Broken (2004) | Intact |
| Safe against tampering | No | Yes |
| Detects accidental corruption | Yes | Yes |
| Relative speed | Faster | Slower, but rarely the bottleneck |
| Used by TLS certificates | No longer | Yes |
| Recommended today | Only for non-security checks | Yes, the default choice |
What "MD5 is broken" actually means
It does not mean MD5 stopped working, and it does not mean someone can turn a hash back into your file. It means an attacker can construct two different files that share one MD5. That single property is what a security check depends on.
So if a download page publishes an MD5 and an attacker controls the file, they can serve you a malicious file whose MD5 still matches. With SHA-256 that is not currently possible. If you are only checking that a file copied across a flaky network arrived intact, no attacker is involved and MD5 is perfectly adequate.
Which one to pick
Choose SHA-256 when
- ›Verifying a download against a publisher's checksum
- ›Anything security-relevant or legally meaningful
- ›Audit trails, evidence handling, compliance records
- ›You simply are not sure which to use
MD5 is still fine when
- ›Detecting accidental corruption after a copy
- ›Finding duplicate files on a drive
- ›The other side only publishes MD5
- ›Cache keys and internal fingerprints
[1] SELECT FILE(S) TO HASH
Select one or multiple files to hash from your system, or drag and drop files below
[2] CHOOSE YOUR HASH FUNCTION
[3] LAUNCH THE HASHING PROCESS
FAQ
Is SHA-256 better than MD5?
For security, yes, without qualification. SHA-256 has no known practical collision attacks while MD5 has had them since 2004. For merely detecting accidental corruption, both work and MD5 is faster.
Why is MD5 still used everywhere?
Inertia and speed. MD5 is embedded in decades of tooling, produces a conveniently short 32-character string, and remains genuinely appropriate for non-adversarial integrity checks, so it has never fully disappeared.
Can two different files have the same SHA-256?
Mathematically such collisions must exist, because any-length input maps to a fixed 256-bit output. But no one has ever found one, and no known technique makes finding one feasible. For practical purposes a SHA-256 match means the files are identical.
Is SHA-256 slow for large files?
Rarely enough to notice. On modern hardware disk read speed is almost always the limiting factor rather than the hashing itself. If you are hashing very large archives on a 64-bit machine, SHA-512 is often even faster than SHA-256.