SMOG Readability Calculator estimates how many years of education someone needs to understand a text. SMOG, the Simplified Measure of Gobbledygook, counts words with more than two syllables and turns that count into a reading grade level. Health communicators rely on it because clearer grade scores help materials reach more people without heavy editing cycles.

What Does SMOG Actually Measure?

SMOG is a readability formula from the 1960s. It looks at words with more than two syllables and estimates a document’s reading grade level. That grade maps to years of schooling the average reader would need. Pretty simple idea, and it still holds up for plain writing checks.

When Should You Use SMOG?

You can run SMOG while you draft, when you compare options, or when you audit how clearly a team writes. For general audiences, the common goal sits at 8th grade or lower.

• Flag readability issues as you draft materials
• Compare pieces you might give the same audience
• Assess how clearly your organization communicates

Why Choose the SMOG Formula?

SMOG is quick and simple next to other readability formulas. You don’t count every word or every syllable in the full document. You get easy quantitative data that points you toward clearer writing without a long scoring session.

How to Score Long Documents

For texts with at least 30 sentences, you sample thirty lines, count the heavy words, then run the formula. Here’s the path if you’ve never scored a long piece before.

Choose Thirty Sentences First

1. Pick 10 sentences from the start of the document.
2. Pick 10 sentences from the middle section.
3. Pick 10 sentences from the end.
4. Copy them into a new file or underline them on paper.
5. Treat periods, question marks, exclamation points, or line breaks as sentence ends.

Count Words Over Two Syllables

• Highlight every word with more than two syllables
• Count hyphenated words as one word
• Include numbers as if they were spelled out
• Include proper nouns in the tally
• Spell out abbreviations unless the audience treats them like words, e.g. COVID or TV

Apply the Simple Formula

Take the square root of your polysyllabic count, then add 3 for the estimated grade level. Twenty-six of those words give a square root near 5.1, plus 3 equals about 8.1, still close to the 8th grade mark. For a tighter score, the calculator path on characterconverter.com handles the math cleanly.

How to Score Short Passages

Same formula as long texts, but you scale as if you had 30 sentences. Work it like this if your passage is short.

1. Count the sentences in your text.
2. Count every word with more than two syllables.
3. Divide polysyllabic words by sentence count for the average per sentence.
4. Subtract your sentence count from 30, multiply by that average, then add the actual polysyllabic total for a hypothetical count.
5. Take the square root of that hypothetical total and add 3 for the grade.

Example: 20 sentences and 80 polysyllabic words average 4 per sentence. Ten missing sentences add 40, total 120. Square root is about 11, plus 3 lands near grade 14.

Where the SMOG Falls Short

SMOG was built for print documents. On digital text you still decide what counts as a word, including URLs and hashtags, and that call needs audience research. Grade scores don’t prove people understand you. You still need community feedback, and readability is only one part of clear communication.

What People Usually Ask About SMOG