Calculate Text Complexity
Estimate reading difficulty with the Flesch reading-ease score. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Calculate Text Complexity
- 1. Paste the passage to score. Paste or type the paragraph or article you want measured into the input pane. Calculate Text Complexity analyzes its sentences, words and syllables as soon as it arrives.
- 2. Read the Flesch reading-ease breakdown. The output lists word and sentence counts alongside the Flesch reading-ease score and a plain-language level like Very easy or Difficult, showing how approachable the passage is to read.
- 3. Copy the score for your notes. Click copy on the output pane and keep the score alongside a draft or style guide, or compare it against a second version of the same passage.
When to use Calculate Text Complexity
Calculate Text Complexity runs a passage through the Flesch reading-ease formula and reports how difficult it is to read, along with word and sentence counts. It's a quick way to check whether writing matches its intended audience before it goes out.
- Checking a blog post before publishing. A blog aimed at a general audience can run its draft through the tool to confirm it doesn't score too dense for casual readers before hitting publish.
- Verifying documentation matches a target grade level. Technical writing style guides often specify a target reading level for user-facing docs. Pasting a help article here checks whether it actually lands in that range.
- Evaluating a marketing email's reading ease. An email campaign written for a broad subscriber list benefits from a lower complexity score. Testing the draft here flags sentences that might need simplifying before sending.
- Comparing two drafts of the same paragraph. After editing a dense paragraph for clarity, running both the before and after versions through the tool confirms the rewrite actually improved the reading-ease score.
Examples
Score a sentence
Input
The cat sat on the mat.
Output
Words 6 … Reading ease 116 Level Very easy
About the Calculate Text Complexity tool
Calculate Text Complexity does its work locally, right in the browser. Estimate reading difficulty with the Flesch reading-ease score. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the Text Tools collection on EditSafely, a set of 211 small, focused Text utilities that share the same instant, private workspace.
There is nothing to configure. Provide the input and the result appears on its own. A worked example further down the page shows exactly what the tool produces for a real input.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Does Calculate Text Complexity cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.