The In-Depth Grammarly Plagiarism Checker Review

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There is no shortage of plagiarism checkers out there.

I’ve reviewed many of them.

But there is only one Grammarly. And it’s our number one choice for plagiarism detection on the Web.

Plagiarism is the act of copying someone else’s work and passing it off as your own. On the academic level, it constitutes cheating and dishonesty. On the corporate level, it is a form of theft that can lead to legal ramifications which could cost thousands.

That’s why it’s so important for businesses that depend on written copy to check every word that they produce for originality. Likewise, it’s important for students on the high school and college levels to be absolutely sure that their content is on the up and up. That’s where a quality plagiarism checker comes into play.

Grammarly is one of the most well-known grammar and plagiarism checkers on the market. Its ability to isolate plagiarized copy and make grammatical corrections has earned it a reputation as a service to be trusted.

Just keep in mind that Grammarly will cost you something to unlock all of their plagiarism-checking features.

So how good is it at rooting out plagiarism? Is Grammarly worth it?

That’s what we’re intending to find out in this Grammarly plagiarism checker review.

ACCURACY 86% out of 86%
DATABASE 16 Billion +
LIMITATIONS 150,000 words
DEVICE COMPATIBILITY Desktop, Browser, Mobile
LANGUAGES Only English
PRICING $11.66/ month (Annual)
See how I evaluated Grammarly →

Plagiarism Checker Criteria

In order to accurately gauge the effectiveness of Grammarly’s plagiarism detection software, we first had to put the system through a series of checks and tests.

When examining a plagiarism checker, you’ll want to know how accurate it is, and how easy the system is to use. We determine that through the following criteria:

1. Accuracy

The most important feature of a plagiarism checker is its ability to root out plagiarism. We tested Grammarly out first hand, using a piece of copy that was stuffed to the brim with plagiarized content. The true test of this system will be how effective it is at marking up this document and letting us know where plagiarism exists.

2. Database

A great plagiarism checker pulls from practically the entire internet. You want to ensure that your checker is testing your content against billions of websites in an effort to sniff out unintentional plagiarism wherever it could be found. Thoroughness is the name of the game. Ensure that your plagiarism detection software leaves no digital stone unturned.

3. Limitations

How many pages/words can this specific checker handle? Are there monthly limits? Daily? Obviously the more you’re able to do, the better. You’re looking for a high monthly volume. Something that could encompass a full-length novel (60,000 words) if need be.

4. Languages

How many languages can your plagiarism checker detect? If it’s limited to just English, you’re selling yourself short. The best plagiarism checkers in the world will be able to sort through many different languages.

5. Device Compatibility

You’re going to want a plagiarism checker that can be used on more than one device. Mobile internet use is huge, and many tablets function the same as a laptop. You want a plagiarism checker that can be used on both desktop and mobile platforms to make for a seamless transition between devices.

6. Customer Service

We tested Grammarly’s customer service department in an attempt to determine how effective they are at resolving questions related to this service. We gauged the speed of their response and the overall quality of their answers.

7. Plans and Pricing

Pricing is one of the most important aspects of a plagiarism detector. What good is the product if it’s completely unaffordable? We will dive deep into Grammarly’s prices and payment options to give you a clear view of what you can expect to pay for all of its features.


Grammarly Plagiarism Checker Pros

There’s an awful lot to like about Grammarly’s plagiarism detection software. From a massive database and highly accurate reporting to a responsive customer support department, this is a well-rounded product that has a lot going for it.

1. Highly Accurate

First, and most importantly, this is a system that does its job. To say I was impressed with my hands on test of this product would be an understatement.

We use the same “control” article to test all of our plagiarism checkers. It’s riddled with copied content and should light up a decent plagiarism detection program like a Christmas tree.

Grammarly decked the halls with boughs of holly, finding a whopping 86% of this content to be taken from other sources.

The process is simple and effective. You start out by pasting your copy into a blank page.

Grammarly plagiarism checker start page

You can also upload the file directly, but for the purposes of this review, I chose to copy and paste. Grammarly immediately set to work, running its full range of services on the document. That covers everything from basic grammar to sentence structure, vocabulary, plagiarism, and more.

You can access the plagiarism results by clicking on a tab in the right-hand corner.

Grammarly plagiarism bad results

Grammarly ripped its way through this content, highlighting passage after passage and letting us know where every bit of suspect copy was taken from.

It determined that this sample article pulled from 11 different sources on the web, and gave us a link to every one of them.

We also tested a piece of original content to gauge the other end of the spectrum. Grammarly only found one similar fragment from one online source to be in question.

Grammarly plagiarism good results

That’s not to say that it’s a perfect system. We found that some of their reporting insights were not thorough enough.

One of my favorite features for a plagiarism detector is the ability to export your findings in a PDF. This is incredibly convenient, particularly for businesses, to hold writers accountable and keep an accurate record.

Grammarly allows you to export a PDF, but it’s for all of their combined services and not just plagiarism. The section on plagiarism is very brief and offers little to no information on what was found, other than the total percentage.

Grammarly plagiarism report PDF

This is not the end of the world, and certainly not enough to move this into the cons section, but it’s less than ideal.

2. Huge Database

When it comes to the size of Grammarly’s database, you have nothing to fear. This is a truly massive system encompassing over 16 billion sources at breakneck speed.

What’s more, this is not a system that anyone else can duplicate. Grammarly’s database is proprietary, meaning that it is exclusive to this service.

To put that number in perspective, there are more than 1.8 billion websites in the world, most with multiple pages, but Grammarly goes beyond that to check databases, journals, ebooks, and more in its quest to find repeated content.

Is it the largest database we’ve seen? No.

Some checkers like Plagly, pull from more than 20 billion sources. But while they have an advantage over Grammarly in terms of quantity, they’re severely lacking in quality.

3. Fair Daily and Monthly Limits

Grammarly’s set limitations are fair and should allow users to check more than the typical workload associated with most businesses and academic programs within the span of a month.

It should also be noted that these limits include not only plagiarism detection, but the rest of Grammarly’s suite of services as well.

In one day users are limited to checking 100 documents which, according to Grammarly, encompasses no more than 50,000 words. That’s nearly an entire novel per day. Howeverm that doesn’t mean Grammarly’s monthly cap is 1.5 million words.

The monthly cap is 300 documents, or 150,000 words, which is still a lot of content to check within such a short period.

How does that equate to a common academic workload?

The average college term paper is between five and seven pages. If you’re writing in 12 point font with double spacing, that gets you around 250 words per page. Single spaced content boils down to around 500 words per page. That means each college paper should be between 1,750 and 3,500 words.

A Grammarly user could write 42 term papers in a one month period and check them with Grammarly.

I hope I never see the inside of that classroom…

4. Available on Multiple Devices

Grammarly can be connected to five simultaneous devices. That’s perfect for a family, a small office, a small academic faculty, or one person with many devices.

Grammarly Device Options

Grammarly is available on both desktop and mobile platforms, so it could be connected to your computer, phone, tablet, and more. This is particularly helpful in the mobile arena for those of you writing papers and professional content on an advanced tablet like the iPad Pro.

If you’re interested in connecting via Android, you have to be running Android 4.0.3 or higher. iOS users need to be running iOS 9.3 or higher to take advantage of Grammarly’s services.

Grammarly has apps for desktop computers, Microsoft Office, and a beta test currently underway with Google Docs. Grammarly is probably best known for its Google Chrome extension, which is a free service that offers limited grammatical corrections.

The plagiarism detector, however, is only accessible through Grammarly’s website, Microsoft Office, or their desktop app.

5. Responsive and Thorough Customer Support

I love a good customer service team. I’m a little spoiled, so I want answers to come fast and I want them to be thorough and respectful.

The easiest way to win my affection from a customer service standpoint is to offer a live chat option. Unfortunately, Grammarly does not have that. It does, however, offer a massive knowledgebase with articles pertaining to almost any question you might have.

Grammarly customer support knowledge base

If you’re unable to find the answer to your question in the knowledgebase, Grammarly has an option for you to reach out to their customer support department via a web form. I reached out with a question about the device compatibility of the plagiarism detector.

Grammarly customer support request submission

I received a confirmation email immediately, letting me know that my question was being processed and would be answered soon. The email also included a link to the knowledgebase and encouraged me to continue looking for an answer in the meantime.

Grammarly support confirmation email

Normally, a customer support department takes between one and two days to respond, so I settled in and prepared to wait this out. I was shocked when I got a response not even an hour later.

Grammarly support email reply

Not only was it a quick response, but it was informative and contained a link. Olivia’s tone was cordial and welcoming and at no time did I feel like this was a “copy and paste” response. Grammarly heard my question and responded in a complete and fast manner.

What more can one ask from a customer service department?

Live chat. But maybe in the future!

Grammarly Plagiarism Checker Cons

While there’s so much to love about this service, it’s not perfect. The one glaring con of Grammarly comes in the form of language inclusion.

1. English Only Language Support

At the moment, Grammarly only offers service in the English language.

With the whole world as a potential market, we feel like Grammarly is selling itself short by limiting it’s support to the English language alone.

English is the third most common language on the planet and is spoken by only 20% of the Earth’s population.

If Grammarly truly wanted to be more inclusive, they should open themselves up to checking for Grammar and plagiarism in other widespread languages, like Chinese and Spanish.

Grammarly Cost, Plans, and Payment Options

Grammarly is known by many as a free service, and that is because it does offer critical grammar and spelling checks at no cost.

However, the plagiarism checking software is only available with Grammarly Premium, a paid plan that includes a lot of extra bells and whistles.

Grammarly premium vs. free plan comparison

The plagiarism checker is only one of many stellar services offered with Grammarly Premium. You also have punctuation, context, and sentence structure checks; vocabulary enhancement; and genre-specific writing checks.

Grammarly Premium Paid Plans

One month with no commitment will cost $29.95. If you purchase a quarterly commitment, the price comes out to $19.98 per month. An entire year of Grammarly Premium boils down to $11.66 per month.

This is a great price for businesses, but the average high school or college student might have a difficult time affording it.

Grammarly allows you to pay with either a major credit/debit card or PayPal.

Do I Recommend Grammarly Plagiarism Checker?


This is a fantastic plagiarism checking system, combing through a massive online database to accurately pinpoint instances of plagiarism and link you to the sites that the copy was pulled from.

In terms of functionality, Grammarly is unsurpassed. It’s a truly great anti-plagiarism system that comes with a slew of additional features that help to create better writers.

I hope that they will eventually offer more languages, and when they do the service can only get better. The only other downside I can see is that Grammarly Premium might be a bit too expensive for students.

But it is the best all-around plagiarism checker on the market today.