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Is Grammarly Plagiarism Checker Accurate?

Is Grammarly Plagiarism Checker Accurate?

I have been using Grammarly Premium for over three years and use the plagiarism checker occasionally.

So, I thought of going all in and reviewing it. Is Grammarly Plagiarism Checker accurate?

The article checks six articles, a PDF document, and a book to check the effectiveness of Grammarly Plagiarism Checker.

What is Grammarly Plagiarism Checker

It is a plagiarism checker available as part of Grammarly’s Premium subscription. It only works in Grammarly’s desktop editor.

How did I take the tests

To make it a fair review, I picked a few articles from the web. However, most articles are from this website.

Checking a five-year-old article

Grammarly Plagiarism Checker Checking a Five Year Old Article
Grammarly Plagiarism Checker Checking a Five-Year-Old Article

In our first test, I picked an article from Android Authority published in 2018. The text is about Google’s revenue in 2017.

Score: Grammarly found the source and displayed it on the page. It gets a 100 score.

Checking a four-year-old article

Grammarly Plagiarism Checker Test 2

In the second test, I took an article from 2019. The original publish date was the 1st of June 2019, and since then, the text has not been changed.

Score: Grammarly stood as expected. The final score for this round is 100.

Checking a three-year-old article

Grammarly Plagiarism Checker Test 3

In this test, I took the article from June 2020. The text is on Snapseed and Lightroom apps and has been live since publication.

Score: Grammarly got 100 out because it found the content and source.

An amazing battle: ChatGPT vs. Grammarly

Checking a two-year-old article

Grammarly Plagiarism Checker Test 4

In 2021, I wrote plenty of articles on Grammarly, but I wanted to ensure that I chose an article and paragraph that had not been changed.

So, I found the article Grammarly vs. Linguix, which compares those two programs.

Score: Grammarly did a great job. It got 100 scores on this test as well.

Checking a year-old article

Grammarly Checking a Year Old Article on the Samsung Website
Grammarly Checking a Year-Old Article on the Samsung Website

This time I took an article from the Samsung website. The article was about Samsung’s revenue in 2021.

Score: Grammarly took 100 out of 100 on this test.

Checking a month-old article

Grammarly Plagiarism Checker Checking a Month Old Article
Grammarly Plagiarism Checker Checking a Month-Old Article

The last test was checking a month-old article on my website. I was worried as the article was new, and after checking, my doubt became my reality.

Score: Unfortunately, the program could not detect the text this time.

Grammarly Plagiarism Checker against PDF

Testing a PDF in Grammarly Plagiarism Checker

To make sure that I’m not leaving anything behind. I took a PDF containing SMS stats. I could not find the publish date for this report, but it looks a few years old.

Score: Grammarly found the text and its source, getting 100 scores in this round.

Grammarly Plagiarism Checker against a book

Testing a Book in Grammarly Plagiarism Checker

The last test of this Grammarly Plagiarism Checker review is checking the text of a published book on the Project Gutenberg website.

The book’s publication date is the 11th of April 2019, which should give Grammarly enough time.

Score: Grammarly Plagiarism Checker could not check the text source here, so it got a 0.

Which is better: Microsoft Editor vs. Grammarly

Is Grammarly Plagiarism Checker accurate

After checking Grammarly Plagiarism Checker against articles, a PDF file, and a book, I concluded that the program is effective on articles and PDFs on the internet.

However, it takes time to store data, so it will have difficulty finding the sources of the newly published content online. In our tests, it passed 6 out of 8.

Does the checker always work

While testing, I found that sometimes it does not work properly.

In a few tests, it showed that the text was 100% original, and after reloading the page or copying the text onto another page, it showed the plagiarized content.

My suggestion is if it says 100% original text, try again, as there is no 100% authentic text. When it works, it finds at least a few percent similarities.

Is Grammarly Plagiarism Checker worth it

If you want a tool to check your grammar, then Grammarly is great. Its plagiarism checker is a plus. However, other tools are worth purchasing if you want a specific plagiarism checker.


Reviewing and testing a program is difficult, as you need data. Although my tests may not fully answer to is Grammarly Plagiarism Checker accurate, it covers a small picture.

I hope the article helped. Please take a moment to share your thoughts below, as it helps me and others.