FNV Hash Generator
Compute FNV-1 or FNV-1a hashes in 32-bit or 64-bit from any text.
How to use the FNV Hash Generator
- Type or paste your text in the box.
- Pick the variant — FNV-1a is the one usually recommended.
- The hash appears as you type; click Copy to grab it.
About the FNV Hash Generator
FNV — Fowler–Noll–Vo, named after Glenn Fowler, Landon Curt Noll and Phong Vo — is one of the great small algorithms. The entire thing is a loop over the bytes doing nothing but a multiply by a fixed prime and an XOR. There are no tables, no rounds, no buffers; it fits in a few lines of any language, runs anywhere, and is fast enough that nobody profiles it. That is why it shows up inside hash tables, symbol tables, caches and interpreters all over the place.
The two variants look almost identical and the difference is easy to miss. FNV-1a differs from FNV-1 only by swapping the order of the XOR and the multiply — that is the whole change. It turns out to matter: doing the XOR first gives noticeably better distribution, especially on short inputs and inputs that differ only in their last byte, which is exactly the situation a hash table faces when keys look like user_1, user_2, user_3. This is why FNV-1a is the variant usually recommended, and why it is the default here. Pick FNV-1 only when you need to match an existing system that already uses it.
Size is the other choice. The 32-bit variants give 8 hexadecimal characters; the 64-bit variants give 16. Wider is not “more secure” — it just means fewer accidental collisions when you are hashing a lot of keys, so 64-bit is worth taking once your key count climbs into the millions. None of the FNV variants are cryptographic. They are designed for speed and spread, they resist nothing, and crafting two strings with the same FNV hash is straightforward. Use them for lookups and bucketing; use SHA-256 when the answer needs to hold up against someone who wants it not to.
Frequently asked questions
What is the difference between FNV-1 and FNV-1a?
Only the order of two operations: FNV-1 multiplies then XORs, FNV-1a XORs then multiplies. That single swap gives FNV-1a better distribution, which is why it is the one normally recommended.
Should I use the 32-bit or 64-bit variant?
32-bit (8 hex characters) is fine for ordinary hash tables. Move to 64-bit (16 hex characters) when you are hashing millions of keys and want accidental collisions to stay rare.
Is FNV secure?
No. FNV is a non-cryptographic hash built for speed. It must never be used for passwords, signatures or integrity against an attacker — collisions can be constructed deliberately with little effort.
What is FNV actually good for?
Hash tables, dictionaries, symbol tables, cache keys, sharding and bucketing — anywhere you need a fast, well-spread number from a string and nobody is trying to trick you.
Is my text sent anywhere?
Your text is sent to our server to be hashed, because browsers cannot compute FNV. It is hashed and immediately discarded — never logged, never stored.