Premise number one for all writers: who are we writing for? Intellectuals? Will they impressed by four-syllable words? Long sentences? If the answer's yes, then I suggest you go straight onto the next blog. But if your goal is to write crisply and clearly then read on...
The Fog Index was invented by an American anti-jargon activist, Robert Gunning
In my opinion, it's only a guideline, not a rule of thumb (who likes those anyway? Kick them out the door for a start), so - as in all of your writing - take this advice as you feel like it:
This is how it works:
- Choose a piece of written work which is at least 100 words long. Count the number of words.
- Divide the total by the number of sentences, which will give you the average sentence length.
- If a long sentence contains two or more complete thoughts (such as those separated by commas, colons or semi-colons) treat each thought as a separate sentence.
- Count the words of three or more syllables (not proper nouns or those compound words: caretaker, antisocial, transatlantic).
- What's the percentage of multi-syllable words (divide the number of multi-syllable words by word total and multiply by 100)?
- Add your average-sentence-length figure to your multi-syllable-percentage figure. Multiply the total by 0.4.
The result is the FOG INDEX for that piece of writing.
A Fog Index of 13 or over means you have a heavy-going reading passage.