The Apple Preview app: how far it goes before you need more

Preview is the app that opens when a file is double clicked and nothing else has claimed it, which is why most people have never looked at what it can do. It gets used as a viewer, and the moment a task looks like editing, something heavier gets downloaded. That habit costs more than it saves, because Preview reaches further than its reputation and then stops abruptly at a few specific places. Knowing where those places are is the whole value of looking at it properly.

The version shipping with macOS 27 is Preview 11.0, and Apple maintains a full user guide for it. What follows is the map: what it opens, what it edits, where the ceiling is, and what sits on the same Mac for the jobs it does not do.

What Preview actually claims to open

Preview registers its supported formats in its own application bundle, and that list is readable without launching anything. On macOS 27 it declares 58 content types.

The predictable entries are there: PDF, JPEG, PNG, TIFF, GIF, HEIC and HEIF, WebP, BMP, ICO, and camera raw. So are several that surprise people. Adobe Photoshop and Illustrator documents are both registered, which means a PSD received from a designer opens for reading without Creative Cloud. OpenEXR and Radiance HDR are registered, so high dynamic range renders open too. JPEG XL and AVIF are both present, which matters for anyone handling modern web image formats.

The older entries are a small archaeology of the Mac: PICT, MacPaint, SGI, Truevision TGA, FlashPix, and the .icns icon format. They are unlikely to come up, but they explain why an ancient file from a backup sometimes just opens.

The absence worth knowing about is SVG. It is not in the registered list. A vector file that opens perfectly in any browser will not open in Preview, and the usual reaction is to assume the file is damaged. It is not. This is the single most common false alarm around Preview, and it takes one glance at the list to rule out.

The PDF side is more complete than its reputation

Most of what people pay for separately is here, and the two features worth knowing first are forms and signatures.

Preview fills out PDF forms, including forms that were never built as forms, by placing text where a field should be. It also holds signatures, captured either with the trackpad or by holding a signed piece of paper up to the camera, and inserts them as an image with a transparent background. Apple describes an enhanced AutoFill that fills stored details with a click. Between those two, the print, sign, scan cycle disappears for most routine paperwork.

The structural editing is real as well. Multiple PDFs combine into one, pages are added, deleted and reordered by dragging thumbnails in the sidebar, and pages are cropped or rotated individually. Text is highlighted, underlined and struck out. Notes and speech bubbles attach to specific spots.

Two file level operations tend to be the reason people reach for other software and then find they did not need to. A PDF can be password protected, with separate controls for opening the document and for permitting actions: select Require Password To Open Document for the first, then set an owner password and decide whether printing and changes are allowed without it. Separately, a PDF's file size can be reduced from inside Preview, which covers the common case of an attachment that is a few megabytes over a limit.

The image side edits the file, not a project

Preview crops, resizes, rotates, adjusts colour, annotates, and converts between file types. It removes the background from an image with a single toolbar click, isolating a person or object in the foreground. It applies colour profiles, and it has a view that shows what an image would look like on a different device.

The structural thing to understand is that there is no project file. Preview works on the document in front of it, which is what makes it fast and also what makes a mistake permanent-looking. Apple's user guide gives reverting changes its own page in the section on managing PDFs and images, and that page is worth reading once before it is needed rather than during the panic.

The practical rule that follows is a duplicate before any edit that removes information. Cropping, resizing down, and background removal all discard data. A copy costs one keystroke and removes the need for a recovery procedure.

The 3D support that almost nobody uses

This is the part of the registered list that reads like a different application. Preview opens Universal Scene Description in all its variants, including the binary and mobile forms, along with glTF and GLB, Alembic, OpenVDB, MaterialX, STL, PLY, and the KTX and ASTC texture formats.

In practice this means a .usdz model sent by a colleague, an STL from a 3D printing project, or a glTF export from a game engine all open on any current Mac with no installation. Apple's guide covers viewing, editing and exporting 3D files, and separately covers sending content from a Mac to Apple Vision Pro for viewing.

Anyone who has watched a coworker install a 500 megabyte viewer to look at one model will recognise how much of that is avoidable. It is worth testing once, on a file that actually matters, so the capability is known rather than assumed.

The viewing features that get overlooked

Reading is the job Preview is used for most and configured for least, and several of its viewing tools replace separate apps outright.

Full text search works inside PDFs, and pages can be bookmarked so a long document reopens where the work was left. The information panel shows a document's metadata, which is where page count, dimensions, and the creating application are found without opening anything else. A PDF can be displayed as a slideshow, which is enough for presenting a deck that already exists as a PDF with no presentation software involved.

Two features cross over from images into text. Preview allows interaction with text inside a photo, so a phrase in a screenshot or a photographed receipt can be selected and copied rather than retyped. And a photo carrying location data can be shown on a map, which answers the question of where a site picture was taken without any third party service.

Smaller conveniences round it out. The frames of an animated GIF can be stepped through individually, which is the fastest way to find the one frame worth keeping. Images can be imported directly from a connected camera or scanner. None of these are headline features, and each one removes a reason to open something else.

The three failures Apple documents

The Preview user guide ends with a short troubleshooting section, and the three entries in it are worth knowing before they happen, because each one looks like a bug and none of them is.

The first is being unable to select or copy text in a PDF. In nearly every case the page is an image, not text: a scan or a photograph wrapped in a PDF container. No amount of clicking will select words that are not there. The fix is optical character recognition, which is a different operation from viewing.

The second is images or PDFs coming out at the wrong size. This is usually a mismatch between pixel dimensions and physical dimensions, since the same image described at one resolution and at another prints at different sizes from identical pixel data. Checking the actual values with sips -g settles the argument faster than adjusting print settings repeatedly.

The third is Go to Page landing on the wrong page. PDFs can carry their own page labels, so a document with front matter numbered separately has a page 1 that is not the first page of the file. The page shown is correct according to the document, which is not the same as correct according to the reader.

Where the ceiling actually is

The honest version of this is a short list, because Preview is not trying to be a design tool. Setting the boundaries out plainly makes the decision faster than discovering each one mid-task.

Task	Preview	What the Mac offers instead
Open an SVG	Not registered	Safari, or a vector editor
Fill and sign a PDF	Yes, including stored signatures	No need to leave it
Combine and reorder PDF pages	Yes, by dragging thumbnails	No need to leave it
Password protect a PDF	Yes, with separate owner password	No need to leave it
Reduce PDF file size	Yes	sips for batch work
Edit layers in a PSD	Opens for viewing only	A layered image editor
Batch convert a folder of images	One file at a time	sips in a shell loop
Recover from a destructive edit	Revert, documented in the guide	A duplicate made beforehand
View a USDZ or STL model	Yes	No need to leave it
Redact text so it cannot be recovered	Drawing over text hides it visually	A tool built for redaction

The last row is the one with real consequences. Covering text with a black rectangle changes how a page looks, not what it contains, and the text underneath can still be selected or extracted. For anything going to a counterparty or a regulator, that distinction is not a detail.

The command line tools installed beside it

Two utilities ship with macOS and cover exactly the case Preview handles badly, which is doing the same thing to many files.

sips is a scriptable image processor at /usr/bin/sips. It queries and modifies raster images and ICC colour profiles, which makes it the direct answer to resizing or converting a folder of images. Reading a file's properties takes one line.

sips -g pixelWidth -g pixelHeight -g format photo.heic

qlmanage at /usr/bin/qlmanage drives the same Quick Look machinery that generates previews in the Finder, and it can produce thumbnails from the command line.

The reason to mention them in an article about Preview is that the two halves solve different problems. Preview is for one file that needs judgement applied to it. The shell is for a hundred files that need the same thing done without judgement. Choosing the wrong half is what turns a five minute job into an afternoon, and having both in reach makes the choice obvious instead of a decision about which app to open.

What to change first

Read the registered format list once, because the two facts that save the most time are that Preview opens PSD and USDZ files and that it does not open SVG. Then decide the rule for destructive edits: duplicate first, always, so revert never has to be the plan. For batch work, go to sips rather than repeating a Preview action, and keep a folder, a shell and a viewer within one window so the switch between the single file case and the many file case costs nothing, which is what Atriens is built around. How it compares with other file managers on that point is set out in Compared with other file managers, and the recurring questions are collected in the FAQ.