A readability checker for interface copy, not blog posts.
Most readability checkers are built for bloggers. This one handles the copy your interface shows people: error messages, form labels, onboarding and empty states. Instant score, no signup.
Paste your copy
An error message from a real product is loaded by default. Replace it with your own error message, form label, empty state or onboarding copy.
Well above the target reading age. UK public-sector guidance aims for reading age 9 (Flesch 60-70) -- this copy scores 15.4, reading age 20.
15.4
0-100, higher is easier
15.3
US school grade
20
years -- approximate
85
5
17 words
0
25
Specific problems found
Common UX-copy failures
- "please try again later" -- this tells someone nothing about what went wrong or what to do next.
- "an error has occurred" -- this tells someone nothing about what went wrong or what to do next.
- "please try again" -- this tells someone nothing about what went wrong or what to do next.
- "contact support" -- this tells someone nothing about what went wrong or what to do next.
Sentences over 20 words (2)
- "In order to proceed with the utilisation of this functionality, users must first authenticate their credentials in accordance with the aforementioned security protocol." -- 23 words. Consider splitting it in two.
- "If you continue to experience difficulties, please don't hesitate to commence the troubleshooting procedure outlined in our comprehensive documentation, or alternatively, initiate contact with our customer support representatives at your earliest convenience." -- 32 words. Consider splitting it in two.
Jargon and complex words (13)
- "at your earliest convenience" → try "as soon as you can" instead.
- "in order to" → try "to" instead.
- "in accordance with" → try "following" instead.
- "please don't hesitate to" → try "feel free to" instead.
- "proceed" → try "go ahead" instead.
- "utilisation" → try "use" instead.
- "functionality" → try "feature" instead.
- "authenticate" → try "sign in" instead.
- "aforementioned" → try "this" instead.
- "termination" → try "ending" instead.
- "commence" → try "start" instead.
- "comprehensive" → try "complete" instead.
- "initiate" → try "start" instead.
Get a human read on your copy, not just a score.
No report generator -- an actual person looks at it.
What the scores mean, and where they come from.
Flesch Reading Ease
A score from 0 to 100 based on average sentence length and average syllables per word. Higher is easier to read. It's calculated as 206.835 - 1.015 x (words / sentences) - 84.6 x (syllables / words).
Flesch-Kincaid Grade Level
The same underlying measurements, expressed as a US school grade: 0.39 x (words / sentences) + 11.8 x (syllables / words) - 15.59. A score of 8 means the text is written at roughly the level of an average 13-14 year old.
UK reading age
We convert the US grade level to an approximate UK reading age (grade + 5 years, which is a commonly used rule of thumb, not a precise conversion). We label this clearly as approximate because it's a translation of a translation. Use the Flesch score as your primary number and the reading age as a rough, more intuitive way to talk about it with colleagues.
The target
UK government content design guidance aims for a reading age of about 9, roughly Flesch 60-70. That target exists for public services used by everyone; we think it's at least as relevant to a product interface, where people are often stressed, in a hurry, or reading on a small screen while doing something else.
These formulas were built for prose, not interfaces.
Flesch and Flesch-Kincaid were developed in the 1940s-70s for continuous text -- training manuals, textbooks, newspaper articles. They measure sentence length and syllable count, and nothing else. A three-word button label and a two-sentence error message will both often score as "very easy" even when one of them is confusing, because the formulas can't see clarity, tone, ambiguity or whether the reader knows what to do next.
Treat every number on this page as a signal, not a verdict. A low Flesch score is a reliable sign of a problem. A high one isn't proof the copy is good -- it just means it isn't failing on sentence length and word complexity. The syllable counter itself is an approximation (vowel-group counting, not a dictionary), so expect it to be slightly wrong on words like "wanted" or unusual names. Read your copy aloud, or better, watch someone else read it, before you trust it.
Common questions
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