How to Screenshot Part of the Screen on Mac
Most partial captures are a rectangle, and a rectangle is often the wrong shape. Snip Studio has six ways to select part of the screen, three of which keep a transparent background, and one that gives you the same exact dimensions every time.
Press ⌃+⌥+A, drag, release. That covers the common case. The rest of this guide is about the five other selection modes and when each is the right one.
Capture part of the screen
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Press the area hotkey
Press ⌃+⌥+A from any app. The screen dims and a crosshair appears with live coordinates beside it.
Works from any application, without switching to Snip Studio. Nothing is captured yet — press esc at any point to back out.
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Drag the region
Click and hold at one corner, drag to the opposite corner, and release. The readout shows the selection's width and height in pixels as you go, so you can stop at a size that matters.
The selection is not bounded by one screen. Start the drag on one display and carry it onto another — the shape follows the pointer across the boundary and the capture comes back as a single image. That works for the shape modes too, not just the rectangle.
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Or select a shape that is not a rectangle
Three modes produce a capture with a genuine alpha channel, so it drops onto any background with no white box behind it:
- ⌃+⌥+C — an anti-aliased circular crop.
- ⌃+⌥+L — a freehand lasso outline with a feathered edge.
- A rounded rectangle with an adjustable corner radius, from the HUD.
Circle captures export with transparency, anti-aliased at the edge. -
Draw the shape yourself with the lasso
Press ⌃+⌥+L and you are not dragging a box — you are drawing. Hold the button and trace around whatever you want, at whatever shape it happens to be. Release, and Snip Studio closes the path for you between where you stopped and where you started.
The crosshair and the magnifier follow your hand the whole way, so you can see exactly which pixel the outline is on as you go round a tight corner.
The outline traces where you draw; release and it closes itself. What comes out is the shape you drew, with a feathered edge and a real alpha channel. That is the point of it: a lasso capture drops onto a slide, a dark page or a product shot without a rectangle of background around it, and without the hard cut-out edge you would get from cropping.
It is the right mode when the thing you want is not rectangular — a chart with a legend beside it, one face in a group photo, a shape on a canvas, a signature. Anything where a box would bring in things you did not want.
If you need a hard edge instead, use area or rounded-rectangle mode; the feathering is deliberate and is not adjustable.
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Use a fixed size when it has to be exact
Press ⌃+⌥+F and you get a rectangle of an exact width and height — 1280 × 720, say — that you position by dragging rather than drawing. The last size you used is remembered, so a series of captures comes out identical.
A fixed-aspect mode is available too, locking 16:9, 4:3 or 1:1 while letting you resize freely.
Drag the frame into place; the dimensions do not change. -
Edit or send it
The capture lands in your library. Copy it to the clipboard, open the editor to annotate or blur, export it as PNG, JPEG, TIFF, WebP or PDF, or drag it straight into whatever you were writing.
Dragging a rectangle around a window by hand always leaves a few pixels of desktop on one side. Press ⌃+⌥+W instead and click the window — you get its exact bounds. See how to screenshot a single window.
Which selection mode for which job
| Mode | Hotkey | Best for |
|---|---|---|
| Area | ⌃⌥A | The everyday rectangle |
| Fixed size | ⌃⌥F | A series that must all match |
| Fixed aspect | HUD | 16:9, 4:3 or 1:1 for slides and video |
| Circle | ⌃⌥C | Avatars, focal detail, transparency |
| Lasso | ⌃⌥L | Cutting an irregular object out of its background |
| Rounded rectangle | HUD | Soft-cornered crops for a deck |
After you release the mouse
A partial capture usually still contains something. Snip Studio reads the text in it on your Mac and lists any email addresses, URLs, file paths, faces or codes it recognised, with masked previews. Blur, pixelate or black them out, and the exported copy is flattened so the hidden content cannot be recovered — while your original stays editable in the library.
The editor also has the annotation tools you would otherwise open a second app for: arrows, numbered steps that increment on their own, dimension markers labelled in pixels, a spotlight that dims everything outside a circle, and a 2× magnifier.
Fixed aspect, for slides and video
Fixed-size capture pins both dimensions. Fixed-aspect pins only the ratio, letting you resize freely while 16:9, 4:3 or 1:1 is maintained.
That is the one you want when the capture is going into something with a fixed shape — a slide, a video frame, a social post, an App Store screenshot — but the thing you are capturing is not always the same size. You frame what matters and the proportions come out right without cropping afterwards.
Repeating the same region
For a series that must all match — a documentation set, a before-and-after pair, a sequence showing one panel changing — fixed size is the tool. ⌃+⌥+F gives you a frame of exact dimensions that you drag into position rather than draw, and it remembers those dimensions until you change them.
Combined with an automation, a run of captures can be framed identically, redacted, and filed into one folder without a save dialog in sight. Conditions on the source app mean the rule only fires where you want it to.
Capturing and the searchable library are free. Automations, the editor, recording, scroll capture and the Safari extension are part of the paid ULTRA upgrades, bought in-app through Apple.
Common problems
The dimensions are double what you selected
Retina displays have twice the physical pixels. A 400 × 300 selection produces an 800 × 600 file. The image is correct — it simply contains more detail than the readout implied. Export at 50% if you want the on-screen size.
The crosshair does not appear
Another app has claimed ⌃+⌥+A. Rebind it in Snip Studio's settings, or start the capture from the HUD instead.
The capture is black
Either Screen Recording permission has not taken effect — grant it, then quit and reopen the app — or the content is protected against capture at the source, as some streaming video is.
The lasso edge looks soft
That is deliberate — lasso captures are feathered so they composite cleanly onto another background. Use area or rounded-rectangle mode if you want a hard edge.
The fixed size is not the one you wanted
Fixed-size mode remembers the last dimensions you set. Change them in the capture bar before you drag, and the new size becomes the one it remembers.
Frequently asked questions
How do you screenshot a selected area on a Mac?
Press ⌃+⌥+A in Snip Studio, drag a rectangle over the area, and release. The capture goes to your library, where you can copy, edit or export it.
Can you take a screenshot of an exact size on a Mac?
Yes. Fixed-size capture, ⌃+⌥+F, gives you a rectangle of an exact width and height that you position by dragging. The size persists between captures.
How do you take a circular screenshot on a Mac?
Press ⌃+⌥+C. The result is an anti-aliased circular crop that exports with a transparent background.
How do you cancel a capture?
Press esc. This works while the crosshair is showing and while you are mid-drag, and nothing is saved.
Why is my screenshot twice the size I selected?
Because Retina displays contain twice the physical pixels. Export at 50% scale if you need the file to match the on-screen dimensions.
Capture modes and hotkeys described from Snip Studio's own documentation and its App Store listing. Last checked 1 September 2026.