Free vs. Paid Antivirus: Avira vs. Bitdefender

Do you really need to pay for Windows antivirus software?

By now, you should know that every PC needs a strong antivirus program to protect it from the malware you’ll encounter while perusing the Internet. But with plenty of free options out there, is springing for a paid antivirus product really worth your money?

To help you decide, we pitted our top pick for free antivirus software — Avira Free Antivirus — against the top inexpensive paid option, Bitdefender Antivirus Plus ($60 list for three PCs; steep discounts available online).

MORE: Best Antivirus Software

We tested both programs on the same Windows 8 Acer Aspire E1 laptop, with a Core i3 processor and 4GB of RAM. We considered not only the programs’ anti-malware capabilities, but also their interfaces and ease of use, features and performance impacts.

Interface Design

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Avira Free Antivirus has a stark interface comprising a pale gray background with red highlights. The features are presented as little more than text in a list, with no graphics or other visual markers to help users navigate. The main interface doesn’t even have an easy “scan now” button. For all its Spartan appearance, however, Avira Free Antivirus is very tidily organized.

Bitdefender Antivirus Plus has a bit more flash. It’s got a gunmetal-gray interface with blue accents and large square icons marking its feature categories, and is both easier on the eyes and easier to navigate from the get-go.

Both products include desktop widgets that provide a quick way to access the full program’s features. Avira’s is a rectangle that pops out of the icon bar, and is designed to be a table of contents for all Avira products installed on a computer. If you only have Avira Free Antivirus, however, some of these icons will be grayed out. Bitdefender’s widget is a slick gunmetal-gray circle that only indicates the computer’s protection status: green for all’s good, yellow for warning, red for problem.

Winner: Bitdefender Antivirus Plus. Its interface is easier to use and more attractive.

Antivirus Protection

Now to the heart of the issue: Which product is better at detecting and stopping malware?

For that we turn to AV-Test, an independent German lab that regularly assesses major antivirus programs.

In an October 2014 study conducted on Windows 8.1, AV-Test looked at and . These are higher-tier versions of Avira Free Antivirus and Bitdefender Antivirus Plus 2015, respectively, but they use the same antivirus engines as the less expensive products. The results should be comparable to the products we’re assessing here.

AV-Test found that both Avira Antivirus Pro and Bitdefender Internet Security were able to catch 100 percent of the widespread, common malware that AV-Test threw at them.

Pitted against samples of zero-day malware (which antivirus engines have never before encountered), Avira Antivirus Pro caught 99 percent, while Bitdefender Internet Security scored 100 percent.

Both products scored over the industry averages for widespread detection (99 percent) and zero-day detection (96 percent).

Malware Detection Performance Compared

Swipe to scroll horizontally
Avira Antivirus Pro Bitdefender Internet Security
Zero-day malware99 percent100 percent
Widespread malware100 percent100 percent

Winner: Bitdefender Antivirus Plus. Bitdefender offers slightly stronger zero-day malware protection, but the free product is just about as robust.

Performance Impact

No matter the features or the malware-detection capabilities, no one wants a program that slows down a PC every time it’s run. That’s why we tested the performance impact of Avira Free Antivirus and Bitdefender Antivirus Plus while they scanned for malware.

Both were run on the same Windows 8 Acer Aspire E1 laptop, which featured an Intel Core i3 processor and 4GB of RAM. We used two different performance tests on each program: one established by PCMark 7 benchmarking software, and our own custom OpenOffice test that matches 20,000 names with addresses.

Before any antivirus program was installed, the Acer Aspire E1 scored a 2,172 on PCMark 7. During an Avira Free Antivirus quick scan, that score dropped slightly, to 2,118. A Bitdefender Antivirus Plus quick scan, by comparison, had an even lighter impact, resulting in 2,155. (Higher is better.)

During Avira’s full antivirus scan, the PCMark 7 score dropped much more steeply, to 1,447. Bitdefender’s full scan saw a drop, too, but it was lighter than Avira’s, at 1,669.

Our OpenOffice test yielded comparable results. Without any antivirus program running, the Acer Aspire E1 completed our test in 8 minutes and 35 seconds. During an Avira quick scan, that increased to 9 minutes flat. A Bitdefender quick scan resulted in a faster time of 8:40. (Less time is better.)

When we ran an Avira full scan, the OpenOffice test completion time increased to 10:25. Bitdefender again came out on top, with its full scan completing in 8:59 — 1 second faster than Avira’s quick scan.

Performance Impact Compared

Swipe to scroll horizontally
PCMark 7 Quick Scan*PCMark 7 Full Scan*OpenOffice Test Quick Scan**OpenOffice Test Full Scan**
Avira Free Antivirus2,1181,4479:0010:25
Bitdefender Antivirus Plus2,1551,6698:408:59

* Higher score is better for the PCMark 7 test.
**Lower time is better for the custom test.

Winner: Bitdefender Antivirus Plus. Its full scan was faster than the Avira Free Antivirus quick scan.

Extra Features

The best antivirus programs are also holistic security programs that come with extra privacy, performance and protection features, which are in addition to the core antivirus engines.

Avira Free Antivirus has a basic range of special features: an interface for managing the Windows firewall; a mobile management hub; and a browser plugin called Avira Browser Safety that detects and blocks malicious links.

But it lacks some features that are standard for paid antivirus programs. Most importantly, Avira Free Antivirus lacks Web protection, which screens the websites you visit and blocks phishing and other malicious links; and mail protection, which scans incoming and outgoing email traffic for malicious attachments.

Bitdefender Antivirus Plus has both and also offers a trove of security tools. These include a Linux rescue partition that will boot and clean your PC after a seriously compromising malware attack, and a data-protection feature that checks to see if a Social Security number, credit card number or other personal data is being sent from your PC. Bitdefender also offers Safepay, which is a secure browser for making online payments, and Safego, which scans your Facebook wall for malicious links. Lastly, there’s a tune-up tool for improving computer performance.

Bitdefender Antivirus Plus’ star attraction is its Profiles feature, which automatically optimizes system performance, depending on what you’re doing. Under your Work profile, Bitdefender will configure your PC’s processes for the longest possible battery life. When you're watching a movie or playing a video game, Bitdefender will adjust your computer’s resources and delay any antivirus scans to prevent lag.

Winner: Bitdefender Antivirus Plus. No contest.


Bitdefender Antivirus Plus offers users much more than Avira Free Antivirus: a better user interface, a much better selection of security tools, a slightly better antivirus engine and a clearly lighter performance impact.

Then again, Avira Free Antivirus costs nothing. And even though Bitdefender edged it out in detecting zero-day malware, it wasn’t by much. If you’re only looking for antivirus protection and don’t care about extra features, Avira Free Antivirus may be all you need.

Winner: Avira Free Antivirus. It’s hard to beat free.

Overall Winner: Bitdefender Antivirus Plus

As with most things, you get what you pay for when it comes to antivirus software. Our comparisons of the best free product, Avira Free Antivirus, and the best inexpensive paid product, Bitdefender Antivirus Plus, make that clear.

In our five-round contest, Bitdefender Antivirus Plus took four of the rounds, offering a friendlier interface, slightly stronger antivirus protection and much lighter performance impact. You also get many more handy features with Bitdefender, including tools for safer Web surfing and shopping. Avira Free Antivirus is still a strong antivirus option and an excellent choice for people on a limited budget, but Bitdefender wins this face-off overall.

Bitdefender Antivirus Plus
Avira Free Antivirus

Jill Scharr is a staff writer for Tom's Guide, where she regularly covers security, 3D printing and video games. You can email Jill at, or follow her on Twitter @JillScharr and on Google+. Follow us @tomsguide, on Facebook and on Google+. 

Jill Scharr is a creative writer and narrative designer in the videogame industry. She's currently Project Lead Writer at the games studio Harebrained Schemes, and has also worked at Bungie. Prior to that she worked as a Staff Writer for Tom's Guide, covering video games, online security, 3D printing and tech innovation among many subjects.