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Calculate FNV hashes online for any string. Supports FNV1, FNV1a, and various input formats for data validation and hashing applications.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This page calculates an FNV hash from text. FNV means Fowler–Noll–Vo; it maps a sequence of input bytes to a fixed-width value. Select one of four variants: FNV-1 or FNV-1a, each at 32 or 64 bits. The default selection is FNV-1a-64. The variant and width are part of the result: changing either changes the digest, so use the same selection as the system you are comparing against.
FNV updates a running value for each input byte using a width-specific offset basis and prime, retaining the result modulo the chosen width. FNV-1 multiplies before XOR with the byte; FNV-1a XORs first and then multiplies. That processing order is the key distinction between the two names.
The calculator presents lowercase and uppercase hash strings. Its Base64 field encodes the returned hash text for this remote FNV operation; it is not a separate hash algorithm or encryption. RFC 9923 documents FNV as a non-cryptographic hash and is published for information, not as an Internet Standards Track specification.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Paste the text whose hash you need. Spaces, punctuation, capitalization, and line endings are part of the input. The text field does not let you choose a raw-byte, hex, or file input mode for this FNV page.
Select FNV-1-32, FNV-1a-32, FNV-1-64, or FNV-1a-64 to match the receiving program. If a specification or existing record says only “FNV,” verify the exact variant and width before using the value.
Run the calculation, then copy the lowercase or uppercase result as required. Keep a note of the variant alongside a saved digest. Use the Base64 display only when you specifically need that representation of the hash text.
Compare the exact characters, including leading or trailing spaces and newlines, then verify variant, width, and expected text casing. If another program hashes encoded bytes rather than the same text representation, align its encoding and byte sequence first.
Use cases
See how the tool fits into real work and everyday tasks.
A developer can hash a known sample string while checking that two non-security workflows select the same FNV variant and width. Treat the digest as a compact comparison value, not a unique identity for the original text.
A team can record a sample input and its selected FNV variant when documenting ordinary hash-table or test-fixture behavior. The context prevents a 32-bit result from being mistaken for a 64-bit one.
Q&A
Find concise answers to common questions and confusing cases.
No. A hash is a one-way digest operation, not encrypted text that can be decrypted. FNV is explicitly non-cryptographic, so do not use it for passwords, signatures, authentication, or security-sensitive integrity checks.
They apply multiplication and XOR in a different order for each input byte. Use the named variant expected by the other implementation; the names are not interchangeable.
They are separate FNV variants with different widths and constants. Select the same bit width and FNV-1/FNV-1a version as the value you are checking.
Notes
Review scope, result limitations, and important precautions before use.
The text-hashing action sends the entered value for processing outside the text field. Do not submit passwords, private keys, personal records, confidential source text, or other sensitive material. FNV is not a security primitive: collisions can occur, and this hash does not authenticate data or conceal the original input. Choose a cryptographic hash designed for your threat model when security matters.
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