How to Highlight PDF on Mac: Free with Preview, or UPDF When Preview Falls Short

That covers most typed documents. But Preview's highlighter is deliberately basic, and you'll feel the ceiling the moment you try to do anything beyond a plain yellow mark: it locks the highlighter to five colors, it has no real area highlight for scans or images, and it can't attach a note to a highlight you've already made.

I ran into all three while marking up a bank statement on my Mac. Highlighting the typed rows in Preview was instant. Then I wanted to change one yellow mark to red, box a figure inside a scanned page, and pin a comment to a highlight I'd already placed — and Preview stopped me at every one. This guide walks through the full Preview workflow first, shows exactly where it hits a wall, and covers how UPDF picks up each of those three gaps when you need it.

Tested in August 2026 on a MacBook Air (M4, 2025) running macOS Tahoe 26.2, with Preview and UPDF for Mac v2.5.6. Menus and behavior may change in later releases.

Part 1. Which Method Fits Your Mac Highlighting Need

Highlighting on a Mac isn't one job — it depends on what's in the file and how much control you need. Use this table to jump to the right method.

Part 2. How to Highlight a PDF in Preview on Mac (Free, Built-In)

Preview ships with every Mac, so this needs no download and works offline. It handles selectable, typed text well.

Step 1. Open the PDF in Preview — right-click the file, choose Open With → Preview, or drag it onto the Preview icon.

Step 2. Show the Markup toolbar by clicking the Markup (pen-tip) icon near the top of the window.

Step 3. Click the highlighter pen icon. Select the text you want to mark, and Preview snaps a colored block onto it.

Step 4. To switch colors, click the small arrow next to the highlighter icon and pick from the five presets (yellow, green, blue, pink, purple).

Step 5. Save with Command + S. To save a copy for sharing, use File → Export.

Part 3. Where Preview Hits a Wall — 3 Real Limits (Tested on macOS Tahoe)

These aren't bugs — they're the edges of what Preview's highlighter was built to do. All three were confirmed by hand in Preview on macOS Tahoe 26.2 (August 2026).

1. The highlighter pen is locked to five colors. Preview's highlighter offers only yellow, green, blue, pink, and purple — there's no color wheel, HEX input, or opacity control for it. You can reach Preview's full system color palette, but only through a different tool: the Shapes tool. That palette (and its "Show Colours…" wheel) belongs to shapes, not to the highlighter pen, so it doesn't help you recolor an actual text highlight. To get a custom color, you have to abandon the highlighter and draw a semi-transparent rectangle with the shape tool instead.

2. There's no true area highlight — only a shape workaround. For a scanned page, an image, or a table where the text isn't selectable, Preview can't highlight the region. The closest you can do is draw a shape rectangle over it. But a shape rectangle is a separate overlay object floating on top of the page — it doesn't "know" there's content underneath, it can be dragged away freely, and it covers with fill rather than letting the content show through like a highlight. It approximates a highlight; it isn't one.

3. Highlights and notes are separate, unlinked objects. Preview can't attach a bound comment to a highlight. Right-click a highlight and nothing happens — there's no context menu and no floating toolbar. If you want a note beside a highlight, you click the separate Note button and drop an independent sticky, which has no relationship to the highlight at all; they just happen to sit near each other. Open the Inspector sidebar (Command + I) and you'll see them listed as two unrelated rows — one Highlight, one Note. Recoloring or deleting also has to happen row-by-row in that sidebar.

Together these mean Preview is fine for basic reading, but it can't do color-coded review, scan marking, or fast re-editing. For those you need a highlighter with a real custom-color picker, genuine area highlight, and an edit-in-place menu.

Part 4. How to Highlight in UPDF When Preview Falls Short

UPDF for Mac is a full PDF app whose highlighter closes exactly the three gaps above. Treat this as the next step when Preview stops you, not a replacement for quick jobs.

Step 1. Open your PDF in UPDF — if you don't have it yet, download UPDF for free and install it in about a minute — then click Comment in the top toolbar.

Step 2. Custom color and opacity. Click Highlight, mark your text, then open the color panel. Beyond the presets you get a full color wheel, sliders, a swatch grid, and an eyedropper for any exact color, plus an opacity control — so you can keep separate color codes for separate kinds of notes.

Step 3. Area highlight for scans and images. With Highlight active, drag a box over the region — UPDF places a real area highlight over a scanned page, figure, or table, not a loose overlay.

If the scan has no text layer and you need selectable, searchable text underneath, run OCR first (top toolbar → Tools → OCR), then highlight the recognized text normally.

Step 4. Recolor or attach a bound note. Click any existing highlight and a floating menu appears right on it — change the color, adjust opacity, attach a sticky-note comment that stays linked to that highlight, copy the marked text, or delete it, all in one place. This is the piece Preview has no equivalent for.

On Mac, UPDF also shows keyboard shortcuts next to each markup tool (highlight is ^⌘H, strikethrough ^⌘S, and so on), and a selected highlight or shape can be nudged into precise position with the arrow keys — small touches that add up over a long document (confirmed in our own testing on UPDF for Mac v2.5.6).

To see the workflow, watch the example of below.

Free vs. Pro for highlighting: UPDF's free version highlights and annotates fully — every markup tool above is usable for free; the only catch is a trial watermark when you export. Pro removes that watermark and is US$49.99/year or US$79.99 one-time, with one license covering Windows, Mac, iOS, and Android across up to four devices.

Download UPDF for free to try custom colors and area highlight on your own Mac file — installation is free, and Pro features are available when you need watermark-free export.

Part 5. Preview vs. UPDF on Mac — Quick Comparison

Both highlight typed text well. The difference shows up the moment you need custom color, scan marking, or fast re-editing.

If you'd rather compare highlighters across both Mac and Windows before committing, see our hands-on comparison of 10 PDF highlighters, which tests cross-page highlighting, area highlight, and color depth side by side.

Part 6. Edge Cases — When Highlighting Fails on Mac

Real situations that stop a highlight cold, and what actually fixes them:

• "Why can't I select the text on my scanned lecture notes?" The page is an image with no text layer, so a text highlighter has nothing to grab. Use area highlight to mark the region visually, or run OCR first to create selectable text, then highlight normally.
• The file won't let you highlight at all. It's likely permissions-protected. You'll need to enter or remove the restrictions first — and only do this on files you own or are authorized to edit.
• Highlights vanish or don't print in another reader. Preview sometimes stores marks as annotations that another app renders differently. When you need them permanently baked in, export a flattened or standard PDF copy rather than relying on the annotation layer.
• You want to highlight the image itself, not text on a page. That's a general, cross-platform task rather than a Mac-specific one — see how to highlight images and scanned PDFs for the full workflow.

Part 7. FAQs

Conclusion

The clean way to think about highlighting on a Mac: start with Preview for free, built-in marking of typed text — it's genuinely good at that. Reach for UPDF the moment you hit one of Preview's three walls: you need a custom color instead of the five presets, you need to mark a scanned page or image region, or you need to recolor and attach a note to a highlight you've already made. They aren't rivals so much as two stages of the same workflow — Preview for the quick pass, UPDF when the document asks for more.

Download UPDF for free to try area highlight and custom colors on your own Mac document — installation is free, and Pro removes the export watermark when you're ready.