Readability Calculator
The Flesch Reading Ease score and the school grade it corresponds to, with the sentence and syllable measurements behind them.
Results
What this tool does
Rudolf Flesch published his reading ease formula in 1948 and it is still the measure written into plain-language rules in several countries. It rests on two things a computer can count exactly: how long your sentences are and how long your words are. Paste a text and this page gives you the score, the equivalent school grade, and the two measurements that produced them — because when the score is low, knowing whether it is the sentences or the vocabulary tells you what to fix.
Formula
Flesch Reading Ease = 206.835 − 1.015 × words per sentence − 84.6 × syllables per word; Flesch-Kincaid Grade = 0.39 × words per sentence + 11.8 × syllables per word − 15.59
Variables
| Symbol | Meaning | Unit |
|---|---|---|
text | Your text | — |
OUT | Reading ease | — |
GR | School years needed | — |
WS | Words per sentence | — |
SW | Syllables per word | — |
SE | Sentences | — |
WO | Words | — |
SY | Syllables in all | — |
LW | Words of three syllables or more | — |
LS | Share of them | % |
LO | Longest sentence | — |
Worked example
- Your textThe cat sat on the mat. It was a warm day and the sun came through the window. The dog watched from the door but did not move, because the floor by the fire was the best place in the house and he knew it.
- Reading ease101.4
- School years needed2.8
- Words per sentence15.00
- Syllables per word1.07
- Sentences3
- Words45
- Syllables in all48
- Words of three syllables or more0
- Share of them0.0 %
- Longest sentence27
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
Frequently asked questions
What does the score mean?
Higher is easier. Flesch set the scale so that 90 to 100 is comfortable for an eleven-year-old, 60 to 70 is plain English that most adults read without effort, 30 to 50 is the register of academic and legal writing, and below 30 is hard going for almost everyone. The second figure translates the same measurement into years of schooling, which is often the easier one to act on: if a leaflet for the general public comes out at fifteen, it is written for the wrong reader.
Does it work on languages other than English?
The arithmetic will produce a number, but the number will not mean what it means in English. Flesch calibrated the constants against English readers and English syllable patterns; Portuguese, Spanish and French all have longer words on average, so the same prose scores lower than it deserves. Adaptations exist for other languages with different constants, and this page does not implement them — treat the score as an English measurement, or use the words-per-sentence line, which travels better.
How are syllables counted?
By approximation, because English has no exact rule. Each run of vowels counts as one syllable, a silent "e" at the end is discounted, and no word ever counts as fewer than one. This is the classic method every Flesch implementation uses, and it gets words like "business" and "queue" wrong. Over a paragraph the errors mostly cancel; over a single sentence they do not, so a short text gives a shaky score.