To write clearly and well, generally use short words and short sentences.

To check your own clarity in writing:

Count how many words you use in an average sentence.

To do that, check any 100 words you have written, in a report or letter.

Divide that 100 by the number of sentences used.

Then count how many "complex" words you have used for every 100 words you have written (a "complex" word is one with three syllables or more-not counting words with capital letters).

Add the two totals together, and then take four-tenths of the total. That is your Fog Index.

For example: if you average 20 words to a sentence, and ten complex words in every 100 words, your total is 30. Four-tenths of this is 12. That is your Fog Index. Reader's Digest has a Fog Index of between 8 and 9. Time magazine is about 11. If you're higher than 13 you're hard to read. Churchill's quote opposite has a Fog Index of 3.2. Except where quoting others, this book generally has a Fog Index between 8 and 10.

*Joseph Peart and Jim R. McNamara, in The New Zealand Handbook of Public Relations, published by Mills Publications, Lower Hutt, New Zealand (1987), attribute the invention of the Fog Index to Robert Gunning, an American businessman.