How to Compress Photos, Video and PDFs on Mac

One word, three different problems

A photo, a video and a PDF are big for completely unrelated reasons, and the fix that works on one does nothing for the others.

A photo is made of pixels and a quality setting. A modern camera spits out a file that captures vast amounts of detail, and the quality setting decides how heavily to compress that data to save space. A video is a bitrate over time. It is a constant stream of megabytes consumed per second, stretching out over minutes or hours, which is why it easily dwarfs everything else on your drive. A PDF is entirely different. It's a digital container. It usually gets large because of the unoptimized images sitting inside it, not the plain text wrapping around them. You cannot treat these three as the same problem.

What your Mac already does

Your Mac already knows how to shrink all three formats. The tools are built right into the system, and for a one-off job they are often enough. Nobody needs an app just to email a single large screenshot.

Open your terminal. The command line tool sips lives at /usr/bin/sips, and you can point it at any image on your drive. Adding the flag -Z caps the longest side of an image. Pass it -s formatOptions and you set your JPEG quality. It runs instantly and writes a new file.

If you prefer clicking, Preview has an option called "Reduce File Size" hiding right under Export. Finder handles footage. Right-click a movie file and you will find a built-in service sitting at /System/Library/Services/Encode Selected Video Files.workflow. It re-encodes your footage to a chosen size preset. These native utilities exist on every machine Apple ships.

What "Reduce File Size" is actually doing to your scan

That menu item in Preview is a Quartz filter. It lives on your machine at /System/Library/Filters/Reduce File Size.qfilter, and it's a plain file you can read. Open it up and look at the instructions it hands to your Mac.

Every image gets re-encoded with ImageJPEGCompress. The filter applies Compression Quality 0.7 and resamples everything to an ImageResolution 144. The longest side is strictly capped at an ImageSizeMax 2400. These are quoted numbers, not estimates, and the filter applies them blind. It just follows orders.

A scanned invoice comes back soft because the system never asked whether the images could take it. A text-heavy PDF with a few small graphics can actually come out bigger. The filter grabs those tiny, efficient files and re-encodes them into JPEGs whether it helps the file size or not. If you run a manual through it, you degrade every single graphic it contains.

Zipping does not do what people think

A JPEG, an MP4 and most modern PDFs are already compressed. Putting them in a ZIP saves almost nothing. You get a tidy container, not a smaller file.

Zip format is for bundling scattered files into one neat package, and it is meant for formats that genuinely do squash. Text, CSV files, server logs and raw database exports compress beautifully. If you handle those, an archive tool like PressZip from the Cold Brew collection is what you need. It handles ZIP, RAR, 7-Zip, TAR and Gzip. You can browse inside an archive before extracting it, or make password-protected ZIPs with a clean, native macOS interface. But it's an archive tool and not a media compressor. Keep your videos out of it.

When the built-in answer is not good enough

Sometimes you need a smaller file without destroying the data inside it. You need a process that leaves the pixels and the text alone.

TinyImage shrinks PNG, JPEG and WebP files in seconds without losing visible quality. It keeps the same pixels and the same format. A 4000 x 3000 photo comes out 4000 x 3000, and a PNG comes out a PNG. It works through batches, showing you the before size, the after size and the percentage on every row. A bar along the bottom adds up the whole batch. The copy is written beside the original with a suffix you choose, like photo-min.jpg by default. Nothing is overwritten. A taken name is numbered. You can stop mid-run and pick up the rest later without redoing the finished ones. Everything is decoded and re-encoded on your own machine, with no account and no upload.

TinyVideo compresses video without uploading it. Every frame is decoded and re-encoded on your own Mac. The original is never touched, and the copy lands beside it with a suffix. It supports MP4, MOV, MKV, WebM and AVI. It writes H.264 in MP4 with the index up front, so the video starts playing before it has finished downloading.

TinyPDF lets you drop in PDFs and get smaller copies beside the originals. There is no single way of shrinking a PDF that wins on every document, so it tries more than one method and keeps whichever came out smallest. The text stays text. Nothing is ever flattened into a picture and there is no setting that changes that. Pages keep their order, text stays selectable, and your links and outline stay intact. It runs through Apple's own PDF frameworks on your Mac, meaning nothing is uploaded.

What it costs you

Compression is a trade, not a free win. TinyPDF will tell you a document cannot be made smaller. Some PDFs arrive already optimised, and the honest thing is to leave them alone rather than hand back a copy of the same file, so it says so and writes nothing at all.

These apps run completely locally, and they are strictly macOS only. TinyVideo doesn't even ship its own encoder. It uses ffmpeg and walks you through installing it the first time you open it. It gives you one command, copied to your clipboard, and the app notices the moment it appears. Bundling it would have turned a 6 MB download into a 200 MB one.

A massive hard drive masks a lot of bad file habits, right up until you have to upload something over a slow connection. If you need local tools that treat your pixels and text with respect, you can find them in the membership.