Read: How to Remove Watermark from PDF in Three Simple Steps
The Test Sample
Our test sample is a 20.05 MB PDF of a single chapter from a high school textbook. This is freely available to the public here. As you can see from the screenshot below, it’s got plenty of high-resolution images interspersed with the text itself. Text compression is easy. The real value of a PDF compressor is in terms of how well it can handle multimedia and this is exactly what we’re testing here. At just over 20 MB, this isn’t a file that’s convenient to email. It brushes right up against the email attachment limit of many email clients—Gmail, for instances, caps attachments at 25 MB.
Our Testing Methodology
We tested each PDF Compressor app in the same way. We ran each app at its default compression setting—we didn’t make any changes to file format or compression quality to eliminate bias. We recorded both the final file size and the time it took to compress the file. The apps were tested on an LG G7, with a Snapdragon 845 processor and 4GB of RAM. This is a high-end 2018 Android flagship smartphone so expect real-world performance to be slower on more budget-friendly devices. Some of the PDF Compressors required the file to uploaded to the cloud. This was done over a 2 Mbps WiFi connection.
The Apps we tested
We tested out the following PDF Compressor apps:
iLovePDF AllPDF Reader PDF Compressor PDF Utils WPS PDF Lite
1. iLovePDF
Who it’s for: Users who want an all-in-one PDF kit We were impressed with iLovePDF right off the bat: It’s got a simple interface with tiles for each PDF function you want to use. Apart from PDF compression, it also allows you to merge and split PDFs, digitally sign PDF documents, annotate them, and convert them to the JPG format, among other functions. For PDF conversion, iLovePDF uses a cloud-based solution. You select your PDF of choice and it uploads it to a server where the actual compression is done. This can lead to slow compression times if you’re using slower internet. We hit a usage cap on an otherwise blazing-fast 100 Mbps line and are stuck with 2 Mbps for the rest of the month. At this speed, it took 2 minutes and 58 seconds for iLovePDF to upload the test file, compress it, and download the compressed version. We expect the process to be much faster with a faster connection. We were very impressed with iLovePDF’s compression solution: It reduced the file size by an incredible 87.5 percent. This took our test file from an unwieldy 20 MB to just over 2 MB. Now that’s real compression. Pros:
Excellent compression results Wide range of additional features like PDF merge and split
Cons:
The cloud-based solution can take a considerable amount of time on a slow net connection Privacy concerns as you have to upload PDF on cloud
Download it here
2. AllPDF Reader
Who it’s for: Users who want a quick, offline PDF compression We were impressed with iLovePDF. But AllPDF’s local compression solution blew us away in terms of speed. Compression time clocked at a mere 3 seconds. AllPDF Reader’s compression reduced the file size by 91 percent, down to just 1.9 MB. However, there is a major problem with AllPDF Reader’s compression. The test file we used did not work with the PDF Compressor. It outputted black pages with no information or pictures whatsoever. Curious about whether or not the option was completely broken, we tried out another test file, Tanzania’s Human Development Report, available from the UNDP website here. Now, at Just 559 KB, this is already a fairly optimized PDF, with just a few images and tables. AllPDF Reader’s compressor did work here, but only reduced the file size by about 10 percent, down to 508 KB. We tried out its other features too, like JPG conversion and these seemed to work fine. Nevertheless, we’re holding off recommending AllPDF because its compressor doesn’t seem to handle large PDFs very well. Pros:
Offline solution Works fast
Cons:
Doesn’t work with all PDF files, especially larger ones
Download it here
3. PDF Compressor
Who it’s for: Users who want a single-purpose app for PDF compression The name says it all with this app. Unlike the others in our list so far, PDF Compressor really is a single-function app. It compresses PDFs, end of story. Just like iLovePDF, it makes use of a cloud-based solution. But just how well does it perform? Sadly, not as well as we’d have liked. For starters, it took a ridiculously long 5 minutes and 10 seconds for the end to end process, from uploading the PDF to its server to compression and download. Furthermore, the compression output was far from satisfactory. iLovePDF achieved a stellar 87 percent compression ratio. Here, we’re looking at a mere .89 percent reduction in size, down to 19.87 MB. Overall, it’s hard to recommend PDF Compressor. Even if it’s single-purpose solution, iLovePDF just does a better job. And even if AllPDF Reader is less reliable, it offers so many more additional PDF functions. We expect PDF Compressor might work better with more text-heavy files, but as it stands we suggest staying away from it. Read: 10 Best PDF Reader Apps for Android Smartphones and Tablets Pros:
Dedicated to PDF compression
Cons:
Very slow Poor compression ratio with our sample PDF
Download it here
4. PDF Utils
Who it’s for: A viable alternative to iLovePDF, for users who want a multipurpose PDF toolkit What we’ve seen so far is that there really is no ideal PDF compressor—they each have pretty major flaws. We think PDF Utils is the most balanced option so far. For starters, it uses offline PDF compression like AllPDF Reader, making for lighting fast compression. We clocked compression speed at just 3 seconds, a tying with AllPDF Reader. However, unlike the earlier item, PDF Utils can handle larger PDFs with relative ease. Our high school textbook sample was successfully converted and the output was legible. The compression ratio is also moderate. PDF Utils brings the file size down to 8.49 MB, a 57.7 percent reduction in size. There is one caveat here. While black and white images are handled well, color images appear to have their colors inverted. Unless your PDF has a lot of critical color-sensitive items, like color-coded tables, this isn’t too bad of a compromise, though. Pros:
Very fast offline solution Moderate levels of compression
Cons:
Color images have their colors inverted
Download it here
5. WPS PDF Lite
Who it’s for: Users who are already in the WPS office app ecosystem WPS PDF Lite is the slimmed-down version of WPS’ PDF reader suite. Unlike its bigger brother, WPS PDF Lite has a more focused set of features. It’s still got a few tricks up its sleeve though, including PDF camera scanning and digital signing, apart from PDF compression. If you’re looking for a consistent experience, this is a decent option if you’re already invested in the WPS app ecosystem—their office apps, particularly their word processing and presentation apps are among the best on Android. Let’s see how PDF compression fares, though. Taking just 6 seconds, it’s pretty clear that WPS Office is an offline compressor. While it’s fast, it’s not very efficient. The standard compression setting only reduces our PDF to 19.5 MB, a miserable 2.7 percent. This is still better than PDF Compressor’s frankly laughable less than one percent result. Both PDF Compressor and WPS PDF Lite have good Play Store reviews—they’re both above 4 stars. We strongly suspect that the poor output here is because of their inability to handle image compression effectively. Going by the number of positive reviews, we still think its worth giving both these options a chance, especially if you’ve got text-heavy PDFs. Pros:
Easy to integrate with the rest of the WPS app suite Fast, offline compression
Cons:
Very low compression ratio with our sample PDF
Download it here
Conclusion:
It’s hard to decide on which of these is the best PDF Compressor app on Android. What we learned from our PDF compression experience is that most compressor apps on the Play Store have lots of compromises—the decision comes down to what you’re comfortable missing out on, rather than what’s best. We’re noting here that the cloud-based solutions like iLovePDF and PDF Compressor can take more time, especially if you have poor connectivity. There’s also the privacy issue involved with sending potentially sensitive PDFs to an unknown server. Overall, though, the best cloud-based solution, and the best overall is iLovePDF. It’s quite slow, but it gets the job done: With over 90 percent compression, it still manages to retain image detail. PDF Utils is our pick for an offline compressor. It’s much faster than iLovePDF and compression levels are still reasonable. However, the color inversion issue could be a dealbreaker. Why limit yourself to compressing PDFs? Check out our list on the best image compressor apps here to find out how to compress your images, too. Read: Best PDF Editor Apps For Android
