Grammarly vs ProWritingAid Readability Tools

Grammarly and ProWritingAid are grammar checkers first. Both also report readability, but in different ways. Grammarly gives you one score. ProWritingAid gives you a report with four.

This post covers what each tool's readability feature reports, what the free plans include, and what neither tool measures. Everything about the two products comes from their own websites, read on 8 October 2026. We did not run the same text through both tools, so this post makes no claim about which one scores more accurately.

What Grammarly reports

Grammarly reports a single readability score. Its own blog says the score is "based on the average length of sentences and words in your document, using a formula known as the Flesch reading-ease test."

You find it in the Grammarly Editor. Open the writing assistant, click Performance, and look under the Readability section. Grammarly's support pages list it with other document statistics, such as word count.

The score runs from 0 to 100, and a higher number means easier text. That is the standard Flesch scale. It is not a school grade level. For how the scale works, see our Flesch Reading Ease guide.

What ProWritingAid reports

ProWritingAid has a dedicated Readability Report. Its help page lists four scores:

• Flesch Reading Ease
• Flesch-Kincaid Grade
• Coleman-Liau Index
• Automated Readability Index

The report also marks up your text by paragraph. The help page says it underlines paragraphs in green, yellow or red, depending on how hard they are to read.

So ProWritingAid gives you three grade-level scores alongside the Flesch score. That helps when you need to hit a grade, such as "8th grade or below."

Side by side

	Grammarly	ProWritingAid
Readability scores	1 (Flesch reading ease)	4
Reports a grade level	Not listed	Yes, three formulas
Where it appears	Performance panel in the Grammarly Editor	Readability Report
Highlights hard text	Not described for readability	By paragraph: green, yellow, red
Gunning Fog	Not listed	Not listed
SMOG	Not listed	Not listed

What neither tool reports

Neither product's pages list the Gunning Fog Index or the SMOG Index.

That matters most in health care. A 2013 review of readability formulas in health information concluded that SMOG "appears best suited for health care applications." The same review found that formulas varied by up to five grade levels on the same text. If your target is written as a SMOG grade, neither of these tools can check it.

It also matters for business and policy writing, where Gunning Fog is a common yardstick for jargon.

To get those two scores, use a calculator that reports them. Ours shows six formulas at once, including SMOG and Gunning Fog, and averages them into one consensus grade. Our guide to the formulas explains what each one measures.

Free plans and prices

These are the prices each company listed on 8 October 2026. Prices change, so check before you buy.

Grammarly

• Free: $0. The plans page lists writing without mistakes, seeing your writing tone, and 100 AI prompts.
• Pro: listed at $12 a month. It adds tone changes, full-sentence rewrites and a style guide.
• Enterprise: contact sales.

ProWritingAid

• Free: $0. The pricing page says "you will only receive suggestions for 500 words at a time."
• Premium: $30 a month, or $120 billed yearly, or $399 as a one-time payment.
• Premium Pro: $36 a month, or $144 billed yearly, or $699 as a one-time payment.

One practical difference: Grammarly's support page says it is an online application and needs an internet connection to analyse your text.

Which one should you pick?

Pick Grammarly if you mainly want grammar, spelling and tone help, and one readability number is enough.

Pick ProWritingAid if you want a grade level as well as a Flesch score, or you want to see which paragraphs are hardest. Its free account limits you to 500 words at a time, so test it on a short sample first.

Use a separate readability calculator if you need SMOG or Gunning Fog, if you need more than four formulas, or if your text is private. Readability Check scores text in your browser and never uploads it. You can also compare two drafts side by side to see how an edit changed the scores.

Whichever tool you use, keep in mind what a grade level is. It measures sentence length and word length. It does not measure whether a reader has the background to follow the ideas. Our post on why grade level isn't reading level covers that gap.

For more tools, see our comparison of seven free readability checkers or the longer Grammarly comparison.

How we checked

We read these pages on 8 October 2026 and recorded only what they said:

• Grammarly's plans page, its readability scores blog post, and its support article on using Grammarly offline.
• ProWritingAid's pricing page, its readability checker page, and its help article on the Readability Report.

"Not listed" means the pages we read did not mention it. It does not prove the feature is missing. If something here is out of date, tell us and we will fix it.