Quick Look on Mac: Preview Files Without Opening Them

Select any file in Finder and tap the space bar: a full preview pops up instantly — no app launch, no waiting. That’s Quick Look, and most people stop at that one trick. It also does fullscreen slideshows, flips through hundreds of images by arrow key, marks up PDFs, rotates photos, and trims video, all without opening a single app.

The basics: space bar in, space bar out

Select a file — Desktop, Finder, even a file in an Open dialog — and press Space. Press Space again (or Esc) to close. Cmd+Y does the same thing if your space bar is busy. The preview handles images, PDFs, video, audio, text, Office and iWork documents, folders (showing size and contents count), and plenty more. Two zoom tricks while a preview is open: pinch on the trackpad, or Option+click an image to zoom into full resolution at the pointer.

While the preview is open you can keep working the keyboard: ↑/↓ (or ←/→ in icon view) moves to the next file and the preview follows. Select a video and space-bar it — it plays right in the panel, with a scrubber.

Browse a whole selection like a slideshow

• Select multiple files (or Cmd+A for the folder), press Space, and use the arrow keys to flip through them — the fastest way to triage a card full of photos.
• Click the grid button in the Quick Look toolbar to see every selected item as thumbnails, then click any one to jump to it.
• Press Option+Space instead and the preview opens fullscreen, with a play button for a hands-free slideshow. Esc exits.

Do real work from the preview

The Quick Look toolbar changes with the file type, and the buttons are genuinely useful:

• Markup (the pencil icon): annotate a PDF or image — draw, highlight, add text and shapes, sign — then save, without ever opening Preview.
• Rotate: one click turns a sideways photo upright (hold Option to rotate the other way). It saves the rotation to the file.
• Trim: on video and audio, drag the yellow handles to cut the ends off a clip — ideal for screen recordings. You’ll be asked whether to replace the original or save a new clip; choose New Clip if you want a risk-free undo (the original stays intact).
• Open with…: the button on the right names the default app, so the preview doubles as a launcher when a look isn’t enough.
• Share: AirDrop, Messages, or Mail the file straight from the preview.

Quick Look beyond Finder

The same space-bar preview works well beyond Finder windows: in Open and Save dialogs (preview a file before committing to it), on Mail attachments, on the Desktop, and in the Trash — which is exactly where you want to double-check a file before deleting it forever. The short version: almost anywhere macOS shows you a file, the space bar will preview it.

Third-party apps can extend the formats Quick Look understands — a code editor might add syntax-highlighted previews for source files, for example. These plug-ins appear as Quick Look extensions in System Settings (under Privacy & Security → Extensions on macOS 13 and 14, or General → Login Items & Extensions on macOS 15 Sequoia), where you can turn individual ones on or off — worth knowing, because a misbehaving extension is the usual culprit when previews break.

If previews stop appearing

Quick Look caches thumbnails aggressively, and its preview server occasionally wedges — blank panels or generic icons where previews should be. Two Terminal commands reset it; the walkthrough is in Quick Look not working on Mac.