How-to · Multi-display · macOS 27

How to span one wallpaper across two (or three) monitors on a Mac

macOS gives each display its own wallpaper and Apple’s guide shows no span option; Show on all Spaces just repeats one picture on every screen. To span, cut one crop per display at its native resolution and set each on its own screen. Apps can do the cutting; Mac+, which we make, spans a moving scene or video.

A spanned wallpaper on a Mac is two or three ordinary wallpapers cut from one picture so that they line up. Below: the cut for identical screens, the fix for screens of different sharpness, the bezel gap, then the apps that do it for you. Apple’s guides and the app pages were read on 29 October 2026.

By Adrien PennetiermacOS developer, creator of Mac+

Updated 2026-10-29 · 7 min read

Mac+ Waves scene on a single Mac display: grey and white bands rolling like a swell behind a month calendar widget, a weekend countdown card and two desktop icons, under a French-language menu bar — Waves, one of the 15 Mac+ scenes, captured on one display. Across two screens, Mac+ continues a scene like this from one to the next instead of repeating it.

Does macOS have a span option for wallpaper?

No. Apple’s macOS 27 wallpaper guides, read on 29 October 2026, list Dynamic Wallpapers, Your Photos, the aerials, Mac, Shuffle Aerials, Pictures and Colors, and no setting that spreads one picture over several displays. The one multi-display switch they document does the opposite: Apple says to turn on Show on all Spaces “to use the same wallpaper on every desktop space and display.” The macOS 26 Tahoe guide uses the same wording.

So a wide panorama is handled like any other picture: each display shows its own copy, sized to that screen, and nothing carries over from one screen to the next. The workaround is to stop giving macOS one wide picture and give it one crop per display instead. Two settings come first.

Extend the desktop, don’t mirror it. Apple separates video mirroring, which shows “your entire desktop on each display”, from an extended desktop. A split picture needs the extended one: open System Settings, click Displays in the sidebar, click the name of the display and check the Use as pop-up menu.
Turn Show on all Spaces off. With it on, every display receives the same picture, which is exactly what a spanned wallpaper must avoid.

Putting a different picture on each display is covered in the multi-monitor wallpaper guide, and Spaces have a guide of their own. This page is only about making the pictures line up.

How do I cut one picture for two identical monitors?

Make a master image as wide as the screens put together and as tall as one of them, then cut it at every screen width. For two 27-inch 4K monitors (3840 × 2160 each), the master is 7680 × 2160: the left crop runs from pixel 0 to 3839, the right one from 3840 to 7679. Each crop then has exactly the shape of its screen, so there is nothing left to trim.

Master size for identical screens side by side, without bezel correction
Setup	Each screen	Master image	Cut at
Two 1080p monitors	1920 × 1080	3840 × 1080	x = 1920
Two 1440p monitors	2560 × 1440	5120 × 1440	x = 2560
Three 1440p monitors	2560 × 1440	7680 × 1440	x = 2560 and 5120
Two 4K monitors	3840 × 2160	7680 × 2160	x = 3840
Two Studio Displays	5120 × 2880	10240 × 2880	x = 5120

Size the crops from the screen’s native resolution, not from the value picked in Displays settings. Apple describes that setting as the one that “determines the size of text and objects on your screen”; on a Retina display it is a scaled value, smaller than the panel’s real pixel grid. The wallpaper size guide explains the difference.

A monitor turned to portrait takes a tall crop, 2160 × 3840 for a 4K panel, placed in the master where it stands on the desk.

What is the native resolution of my Mac’s screen?

Apple prints it on each model’s tech-specs page, together with the pixel density you need when the screens differ. These are the current figures, read on 29 October 2026. For a monitor from another maker, take the native resolution from its spec sheet.

Native resolution of current Apple screens, from Apple’s tech-specs pages (29 October 2026)
Screen	Native resolution	Pixel density
MacBook Neo	2408 × 1506	219 ppi
MacBook Air 13-inch	2560 × 1664	224 ppi
MacBook Air 15-inch	2880 × 1864	224 ppi
MacBook Pro 14-inch	3024 × 1964	254 ppi
MacBook Pro 16-inch	3456 × 2234	254 ppi
Studio Display	5120 × 2880	218 ppi

If a spec sheet gives only the size, work the density out: the diagonal in pixels divided by the diagonal in inches. A 27-inch 2560 × 1440 monitor gives √(2560² + 1440²) ÷ 27, about 109 ppi; a 27-inch 4K monitor about 163 ppi.

What if my two screens differ in size or sharpness?

Then decide what has to match: pixels or physical size. When the two pixel densities are close, plain pixel crops line up. A MacBook Air 13-inch (224 ppi) and a Studio Display (218 ppi) differ by less than 3 %, so a 7680 × 2880 master cut into a 2560 × 1664 crop and a 5120 × 2880 crop reads as one picture. If the bottom edges of the two pictures are level on your desk, the Air’s crop starts 1216 pixels from the top of the master (2880 − 1664).

When the densities are far apart, pixel crops break the picture. A MacBook Neo (219 ppi) next to a 27-inch 1440p monitor (about 109 ppi) would draw the same detail about twice as large on the monitor. Work in physical size instead.

Build the master at the highest density on the desk: 219 ppi here.
For each other screen, take a block of its native width × (master ppi ÷ screen ppi), and the same for the height. For the monitor: 2560 × 2.013 ≈ 5154 and 1440 × 2.013 ≈ 2899.
Export that block shrunk to the screen’s native size, 2560 × 1440. The Neo’s block is exported at 2408 × 1506 as it is. Side by side with no gap, the master is 7562 × 2899.
Place the blocks the way the screens sit. If the Neo’s top edge is 1.5 inches lower than the monitor’s, its block starts 1.5 × 219 ≈ 328 pixels lower in the master.

Set the same layout in Displays settings, so the arrangement you cut for and the one macOS uses agree. Apple’s Arrange option is where you “Arrange the position of the displays”, and it appears only when an external display is connected.

How do I stop the bezels from breaking the picture?

Leave out a strip of the master as wide as the gap between the two pictures. Measure from the last visible pixel of one screen to the first visible pixel of the next (both bezels plus any space between the stands), multiply by the master’s ppi, and skip that many pixels between the crops. A line that crosses the gap then carries on at the right height, as if seen through a window frame.

Two Studio Displays with a 1-inch gap: 1 × 218 = 218 pixels. The master grows to 10458 × 2880. The left crop stays at 0–5119; the right one starts at 5338 and ends at 10457. The strip between them is never shown.

Skip the correction when the picture is mostly sky, water or texture: nothing there needs to line up, and you keep every pixel. If one screen looks soft afterwards, the crop is usually smaller than that screen; the blurry wallpaper guide sorts out the other causes.

Span a still picture across two displays, step by step

Open System Settings, click Displays, click each display’s name and use the Use as pop-up menu so the desktop is extended, not mirrored.
Use Arrange in Displays settings to place the screens the way they sit on your desk.
Write down each screen’s native resolution and pixel density, from Apple’s tech-specs page or the monitor’s spec sheet.
Build the master: for identical screens add the widths; for unlike screens scale each block by master ppi ÷ screen ppi; add the bezel gap if you want it.
Cut one crop per screen, export each at that screen’s native size and name it after its position (left, right).
Open Wallpaper settings and turn off Show on all Spaces. Under Your Photos, click Add Photo, then Choose File, and add the crops.
Set the left crop on the left display and the right crop on the right display. If you use several Spaces, repeat it in each.

Which apps span a still wallpaper for you?

Two current Mac apps state on their own pages that they cut one picture across several displays and set the pieces: SpreadPaper, free and open source, and Multi Monitor Wallpaper, a subscription app on the Mac App Store. Both describe a layout that follows your real setup, which spares you the arithmetic above.

Apps that span one still picture, as stated on each vendor’s page (read 29 October 2026)
App	What its page says	Price as stated	Minimum macOS
SpreadPaper	One image across every display, or a light and dark pair, or a time-of-day schedule; follows the macOS display arrangement; bezel compensation	Free, open source (MIT licence)	macOS 15 Sequoia (version 1.10.1)
Multi Monitor Wallpaper	“Use a single fabulous image across all your monitors”; lay out the monitors to match your physical setup; supports Dynamic Wallpapers	7-day free trial, then a yearly subscription; the in-app purchase is listed at $9.99 on the US App Store	macOS 10.15 (version 4.4.5, notes “Updated for Tahoe”)

SpreadPaper’s site says the app is not signed with a paid Apple Developer ID, so macOS warns at the first launch and you allow it once, as the site explains. The safety guide covers what that warning does and does not tell you. Prices and versions move: read the vendor’s page before you pay.

Can a live wallpaper span two monitors on a Mac?

Not with macOS alone. Apple’s guide says its aerial wallpapers “animate as you lock or unlock your Mac”, and the rest of the time they stand still; it documents no option that carries a moving picture from one display to the next. A picture that keeps moving across two screens needs an app that says it can stretch an animation across displays.

Aerial, free and open source, plays as a screen saver and as a live wallpaper, and its home page lists “stretch one video across every display” among what it does. Version 4.1.9, released on 23 October 2026, needs macOS 26 or later; version 4.0.16 still runs on macOS 15. Two other video wallpaper apps describe something different on their pages: Backdrop lets you “mirror a single backdrop or set different ones for each screen”, and MacWall offers “One wallpaper everywhere, or a different one on each screen.”

Where Mac+ fits, and where it does not

We make Mac+, so read this section as an interested one. It comes last because everything above works without it.

Mac+ can stretch one continuous scene or video across several displays, so a single animation flows from one screen to the next instead of repeating on each. The scenes are rendered on the GPU with Metal, and your own clip can play instead (how to set a video as wallpaper). The animation pauses when the screen sleeps or an app covers it, and the battery cost is very little but never zero; the battery guide goes into it.

Free tier, as listed on the site: 6 animated scenes, 8 palettes, an image background, 6 folder icons, 2 widgets and multi-display.
A video of your own is part of Pro.
macOS 13 or later, Apple silicon and Intel; it runs on macOS 27 Golden Gate and on the MacBook Neo.
Spanning is stated for a scene or a video. For a still photograph, use the cut above or one of the apps in the table.

What was checked for this page, and what was not

Read on 29 October 2026: Apple’s wallpaper and display guides for macOS 27 (and the macOS 26 wallpaper guide for the labels), Apple’s tech-specs pages, and the SpreadPaper, Mac App Store, Aerial, Backdrop and MacWall pages. Mac+ facts come from its site and its maker.

Not done: no picture was split and no app was installed on a real Mac for this page. The crop sizes are arithmetic from the figures above, and what each app does is its vendor’s own description.

↓ Download Mac+ free Mac+ home

macOS 13 or later. Apple Silicon and Intel. Multi-display is in the free tier; your own video is part of Pro.

Frequently asked questions

How do I stretch a wallpaper across two monitors on a Mac?

Cut the picture into one crop per display, each at that screen’s native resolution, turn off Show on all Spaces in Wallpaper settings and set each crop on its own display. Apple’s guide shows no span option (read 29 October 2026); apps such as SpreadPaper do the cutting for you.

Why does my wallpaper repeat on both screens instead of spanning?

macOS gives every display its own wallpaper, and Show on all Spaces puts the same picture on each of them. A wide image is never continued from one screen to the next, so you need one crop per screen.

What size wallpaper do I need for two monitors?

For identical screens, the combined width by one screen’s height: 5120 × 1440 for two 1440p monitors, 7680 × 2160 for two 4K monitors, 10240 × 2880 for two Studio Displays. Add the bezel gap if you correct for it. Unlike screens need one crop each, scaled by pixel density.

Can I span a wallpaper across 3 monitors?

Yes, the same way, with three crops. Three 2560 × 1440 monitors take a 7680 × 1440 master cut at 2560 and 5120; each crop then goes on its own display.

Can a live wallpaper span two monitors on a Mac?

Not with macOS alone: Apple’s aerials animate only as you lock or unlock the Mac. Aerial’s page lists stretching one video across every display, and Mac+, which we make, can stretch one continuous scene or video across several displays.

Is there a free app to span a wallpaper on Mac?

SpreadPaper is free and open source and spreads one image across every display. It needs macOS 15 Sequoia or later and, according to its site, is not signed with a paid Apple Developer ID (checked 29 October 2026). Cutting the picture yourself in any image editor costs nothing either.

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Sources

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