Metrics Explained
Understanding the readability metrics and scores used by Claru
What are Readability Metrics ?
We test how hard your original Document is to read. We also test if after Conversion. We use special Tests that look at things like:
- How long your Sentences are
- How hard your Words are
- How many Syllables Words have
We use 5 different Tests. Each Test checks different things. This helps us make sure your Easy Read Document is really easy to read.
Want to Check Your Document's Readability ?
Use our Free Online Readability Checker to test your Document before converting it. Get all 5 Metrics instantly — no sign-up required.
Try Free Readability CheckerFlesch Reading Ease Score
What it does: This Test shows how easy your Text is to read.
How it works: It looks at how long your Sentences are and how many Syllables your Words have.
The Scores: You get a Score from 0 to 100. Higher Scores mean easier to read.
Why we use it: This Test has been used since the 1940s. Governments and Schools use it all over the World.
UK Reading Levels:
- 90-100 Very Easy (Primary School)
- 80-89 Easy (Year 6-7 level)
- 70-79 Fairly Easy (Year 8-9 level)
- 60-69 Standard (GCSE level)
- 50-59 Fairly Difficult (A-Level)
- 30-49 Difficult (University level)
- 0-29 Very Difficult (Postgraduate level)
Flesch-Kincaid Grade Level (Reading Level)
What it does: This Test tells you what School Year you need to be in to understand the Text.
How it works: It looks at Sentence Length and Syllables to work out Difficulty.
The Scores: Lower School Years mean easier to read.
Why we use it: The US Navy created this Test in the 1970s. We changed it to use UK School Years instead of American Grades.
UK School Year Equivalents:
- Reception/Year 1: Ages 4-6
- Years 2-6: Ages 7-11 (Primary)
- Years 7-9: Ages 12-14 (Secondary)
- Years 10-11: Ages 15-16 (GCSE)
- Years 12-13: Ages 17-18 (A-Level)
- University: Ages 18-22
- Postgraduate: 22+ years
Dale-Chall Readability Score
What it does: This test looks for hard words that people might not know.
How it works: It has a list of 3,000 easy words that most Year 4 children know. If your text uses words not on this list, they are "difficult" words.
The scores: You get a score from 0 to 10. Lower scores mean easier to read.
Why we use it: This test is better at finding difficult words than just counting syllables. It knows which words people actually find hard.
Score Interpretation:
- 4.9 or below Year 4 and below
- 5.0-5.9 Years 5-6
- 6.0-6.9 Years 7-8
- 7.0-7.9 Years 9-10
- 8.0-8.9 Years 11-12
- 9.0-9.9 Year 13 (Sixth Form)
- 10.0+ University level
Gunning Fog Index
What it does: This test finds long words and long sentences that make reading hard.
How it works: It counts words with 3 or more syllables. These are "complex" words.
The scores: Lower school year scores mean easier to read.
Why we use it: A newspaper publisher called Robert Gunning made this test in 1952. It is good at finding writing that is harder than it needs to be.
Target Levels:
- 6-8: Easy to read
- 9-12: Acceptable for general public
- 13-16: Difficult - university level
- 17+: Very difficult - postgraduate
• Newspapers: 8-11
• Popular magazines: 10-13
• Government documents: Should be 12 or less
Automated Readability Index (ARI)
What it does: This test counts letters in words instead of syllables.
How it works: It looks at how many letters are in your words and how long your sentences are.
The scores: Lower school year scores mean easier to read.
Why we use it: The US Air Force made this test in 1967. It is faster for computers to use because it counts letters, not syllables.
What makes it different:
- ✓ Does not count syllables
- ✓ Works well with technical writing
- ✓ Works the same in different languages
- ✓ Easy for computers to use
Why We Use Multiple Metrics
Each test is good at different things:
- Flesch Reading Ease: Most people know this test
- Flesch-Kincaid: Tells you the school year needed
- Dale-Chall: Finds words people do not know
- Gunning Fog: Finds sentences that are too long
- ARI: Easy for computers to use
Using all 5 tests together gives us:
- Better answers
- We can find different problems
- We can check our work
- We know our Easy Read version is better
- Professional results
Easy Read Target Scores
For good Easy Read documents, Claru tries to get these scores:
Flesch Reading Ease
Easy to Very Easy
School Year Level
Age 11 and under
Sentence Length
Short and clear