How is the Polish Fog index calculated?

It uses the standard Gunning Fog structure: 0.4 times the sum of words-per-sentence and the percentage of hard words. The Polish adaptation defines a hard word as one with four or more syllables instead of the English three, because Polish words run longer.

Why four syllables instead of three?

Many ordinary, easily understood Polish words have three syllables, so the English threshold would flag too much common vocabulary as difficult. Raising the bar to four syllables keeps the index aligned with perceived difficulty in Polish.

How are Polish syllables counted?

A syllable corresponds to a vowel nucleus, so the tool counts vowel groups using the Polish vowels a ą e ę i o ó u y. Consecutive vowels are treated as a single nucleus, and every word counts as at least one syllable.

What does the Fog number mean?

It approximates years of schooling. A Fog of 8 suggests text readable around the eighth year of education, while 14 or more indicates demanding, academic prose. Lower numbers mean broader accessibility.

Does my text get uploaded?

No. All counting and scoring run locally in your browser. Nothing is sent to a server, so the tool is safe for confidential or unpublished Polish content.

What is the Polish Gunning Fog Adaptation?

Scores Polish text with a Gunning Fog adaptation that defines a hard word as four or more syllables, reflecting Polish word length. Counts words, sentences, and Polish syllables, then estimates the years of schooling needed to read the text on first pass. It runs free in your browser on Gera Tools, with nothing uploaded.

Polish Gunning Fog Adaptation

Name: Polish Gunning Fog Adaptation
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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The Gunning Fog index estimates how many years of education a reader needs to understand a passage on the first pass. Because Polish words are longer and more syllable-rich than English ones, this tool adapts the “hard word” threshold so the index stays meaningful for Polish text.

Why a Polish-specific adaptation is needed

English Gunning Fog defines a “hard word” as one with three or more syllables. In Polish, many completely ordinary words already have three syllables: człowiek (person), miasto (city), zrozumieć (to understand). Applying the English threshold would flag vast amounts of simple, everyday Polish vocabulary as difficult and produce inflated Fog scores. This tool raises the threshold to four or more syllables, which better separates truly complex vocabulary (legal Latin borrowings, bureaucratic compound nouns) from normal Polish prose.

How it works

The formula is the classic Gunning Fog:

0.4 × ( (words / sentences) + 100 × (hardWords / words) )

Words are Polish tokens, sentences come from terminal punctuation (. ! ? …), and a hard word is one with four or more syllables. Syllables are counted by vowel groups using the Polish vowels a ą e ę i o ó u y, with adjacent vowels forming a single nucleus. The result approximates the school grade or years of education required.

What the scores mean

Fog index	Reading level	Typical context
6–8	Easy, accessible	Children’s books, simple instructions
9–11	Standard	News articles, product descriptions
12–14	Elevated	Academic articles, business reports
15+	Demanding	Legal texts, medical literature

For general Polish audiences, aim for a Fog index below 12. Marketing copy and public information often targets 9–11. Legal and regulatory Polish commonly scores 15 or above.

Worked example

Consider two Polish sentence types. A simple sentence like Idź do sklepu i kup mleko (Go to the shop and buy milk) contains no hard words and is short — contributing nearly nothing to the Fog score. By contrast, a sentence like Niniejszym poświadczam autentyczność przedłożonego dokumentu potwierdzającego tożsamość wnioskodawcy (I hereby certify the authenticity of the submitted document confirming the identity of the applicant) contains several four-plus-syllable words and would push the Fog score well into the 15+ range.

Practical guidance

Check sentence length first. The words-per-sentence component often matters more than vocabulary. Breaking one 40-word sentence into two 20-word sentences immediately lowers the score.
Target one index, then revise. Paste a draft, note the Fog score, shorten the longest sentence, then re-score. Iterate rather than rewriting everything at once.
Not a substitute for human review. Fog scores do not capture idiom difficulty, sentence rhythm, or technical jargon that is short but unfamiliar. Use alongside a human reader from your target audience.

Everything runs locally in your browser — your text is never uploaded.