Flesch Reading Ease: what the score means and how to raise it
Flesch Reading Ease turns sentence length and syllables per word into a score where higher means easier. Here is the arithmetic, a worked example, and what actually moves the number.
Flesch Reading Ease is the oldest readability score still in everyday use, and probably the best known. Rudolf Flesch published it in 1948. Word processors, content tools, and some regulations still use it. It gives a single number where higher means easier. Most everyday text lands between about 0 and 100, though the formula itself has no hard floor or ceiling.
The formula
Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)
Two averages drive it:
- Average sentence length (words per sentence). Each extra word per sentence costs about one point.
- Average word length (syllables per word). This term carries the heavy weight. Going from 1.4 to 1.5 syllables per word costs 8.46 points.
The constant 206.835 simply shifts the scale so that typical texts fall in a convenient range. It has no meaning of its own.
A worked example
Take one stiff sentence:
The committee will reconvene subsequently to evaluate the documentation.
Count it:
- Words: 9
- Sentences: 1
- Syllables: the (1), com-mit-tee (3), will (1), re-con-vene (3), sub-se-quent-ly (4), to (1), e-val-u-ate (4), the (1), doc-u-men-ta-tion (5). Total: 23.
Now the arithmetic:
- Words per sentence: 9 ÷ 1 = 9, and 1.015 × 9 = 9.135
- Syllables per word: 23 ÷ 9 = 2.556, and 84.6 × 2.556 = 216.2
- Score: 206.835 − 9.135 − 216.2 = −18.5
Yes, that is below zero. The sentence is short, but almost every word is long, and the syllable term swamps everything else.
Now a plain version that says the same thing:
The group will meet again later. They will check the papers.
- Words: 11 (6 + 5)
- Sentences: 2
-
Syllables: the, group, will, meet (4), a-gain (2), la-ter (2), they, will, check, the (5), pa-pers (2). Total: 14.
-
Words per sentence: 11 ÷ 2 = 5.5, and 1.015 × 5.5 = 5.5825
- Syllables per word: 14 ÷ 11 = 1.2727, and 84.6 × 1.2727 = 107.67
- Score: 206.835 − 5.5825 − 107.67 = 93.6
The second version has more words and more sentences, yet it scores over 100 points higher. Nearly all of the gain came from shorter words. That is typical of the formula.
Watch out: Scores on tiny samples swing wildly. A single sentence can land far outside the usual range, as you just saw. Score at least a few paragraphs before drawing conclusions.
What the score means
Flesch described his scale in bands, from “very easy” at the top to “very difficult” at the bottom, and linked each band to a rough school level. Here is how Op-Ed Insight labels them:
| Score | Description | Approximate school level (US) |
|---|---|---|
| 90–100 | Very easy | 5th grade |
| 80–90 | Easy | 6th grade |
| 70–80 | Fairly easy | 7th grade |
| 60–70 | Plain English | 8th–9th grade |
| 50–60 | Fairly difficult | 10th–12th grade |
| 30–50 | Difficult | College |
| 10–30 | Very difficult | College graduate |
| Below 10 | Extremely difficult | Professional |
Bands as in the table widely reproduced from Flesch (1948), with its lowest band split in two as many tools do. Scores above 100 and below 0 are possible.
The bands are conventions that come from Flesch’s own descriptions. They are not precise cut-offs. A score of 59 is not meaningfully harder than a score of 61.
Flesch Reading Ease versus Flesch–Kincaid Grade
The Flesch–Kincaid Grade Level uses the same two averages with different weights, and it reports a US school grade instead of a 0–100 scale. The two run in opposite directions: when Reading Ease goes up, the grade usually goes down. They are not a simple conversion of each other, though, because the grade formula gives sentence length relatively more weight.
How to raise a low score
Because syllables per word carries most of the weight, start with words. Then turn to sentences.
Swap long words for plain ones where the meaning holds
Many long words have short equivalents that mean the same thing: “use” for “utilize,” “help” for “facilitate,” “start” for “commence,” “before” for “prior to.” Our plain words list collects hundreds of these pairs.
Before: Participants are requested to familiarize themselves with the materials prior to attendance.
After: Please read the materials before you come.
Keep a long word when it is the right word. “Photosynthesis” has no short synonym, and “pneumonia” should not become “lung sickness” in a medical leaflet.
Turn nouns back into verbs
Words ending in -tion, -ment, and -ance are often verbs in disguise. “Make a determination” becomes “decide.” “Conduct an investigation” becomes “investigate.” The fix removes words and syllables at once. See nominalizations.
Cut padding phrases
“In order to” is “to.” “At this point in time” is “now.” “Due to the fact that” is “because.” Each one inflates the word count and often the syllable count too. The wordy phrases list has more.
Split long sentences at natural joints
Look for “and,” “but,” “which,” and semicolons that join two complete thoughts. Split there. The sentence length checker highlights sentences of 25 words or more so you can find the candidates quickly. See how to write shorter sentences.
Before: The update, which was released on Monday after several weeks of testing, fixes the login problem that some users reported, and it also improves the speed of the search page.
After: Monday’s update fixes the login problem some users reported. It also makes search faster.
What not to do
The formula rewards short words and short sentences whether or not they help. You can push a score up by chopping every sentence in half or swapping precise terms for vague ones. The number improves while the text gets choppier, or less exact, or both. If a change makes the text worse for your reader, undo it, whatever the score says.
Different tools also count syllables and sentences differently, so the same text can score a few points apart in two checkers. Counting syllables explains why, and our methodology page describes how Op-Ed Insight counts.
Try it on your own text
Scores
- Flesch Reading Ease–
Counts used
Hardest sentences
- Paste a few sentences to see which are hardest.