Guide

How to span a wallpaper across multiple monitors on a Mac

macOS gives each display its own wallpaper. This is the whole job of running one image across all of them, from sizing the photograph to lining the picture up across the gaps between the screens.

How macOS handles wallpaper

Each display takes its own image. System Settings sets one image per display, and macOS runs no single image across all of them.

Spanning one image therefore means cutting the photograph into one piece per display, sized to that display's own resolution, positioned to match where the monitors sit on your desk, then setting each piece as that display's wallpaper. An app can do it in a few clicks, or you can do it by hand. Both routes are below.

What you need before you start

The image has to cover the bounding box of your display arrangement: the arrangement in System Settings, in points, times the scale of the sharpest display. Summed widths give the same number only for matched displays side by side. Anything smaller is enlarged to fit, which is where soft wallpapers come from.

Two 1080p side by side: 3840 pixels across
Two 1440p side by side: 5120 pixels across
Two 4K side by side: 7680 pixels across
Three 4K side by side: 11520 pixels across
Two 4K stacked: 3840 pixels across, 4320 tall
A 4K display at 2x beside a 1080p display, both 1920 points wide: 7680 pixels across, because the 4K display is the sharper one
A laptop 1512 points wide beside a display 2560 points wide, both at 2x: 8144 pixels across

Aim a little above the number. Bezel compensation hides a strip of the image behind each monitor's housing, and you want those pixels to exist rather than be invented by the scaler.

Spanning the wallpaper with SpreadPaper

SpreadPaper needs macOS 15 Sequoia or later. It reads your display arrangement and does the slicing for you.

Arrange

Open System Settings, then Displays, and drag the rectangles until they match how the monitors sit on your desk. SpreadPaper reads that arrangement, so getting it right here is what makes everything afterwards line up.

Install

Download SpreadPaper and drag it to your Applications folder. macOS warns you the first time you open it, and the help page walks you past that.

Choose

Open the app and choose your image. The preview draws your displays in their real arrangement with the photograph laid across them.

Position

Drag the image into place, zoom to fill the width and flip it if the composition works better reversed. Aim for a subject that no bezel cuts in half.

Bezel gap

Raise the bezel value until a horizon or a roofline runs through the seam unbroken. This is the step that makes the picture read as one picture instead of two neighbouring ones.

Apply

Click Save & Apply. Each display is rendered at its own native resolution, so a 4K monitor gets 4K pixels and the 1080p monitor beside it gets its own.

Save

Keep it as a preset to bring it back later. From there you can also set a separate Light and Dark wallpaper, or put a set of images on a time of day schedule.

Download for macOS

Two, three or more monitors, portrait and mixed sizes

The same steps spread one image over any number of displays. What changes is the size of the image you need and how you arrange the displays.

Three or more monitors

Arrange all of them in System Settings and choose an image as wide as the whole row. Three 4K monitors side by side want 11520 pixels across. Set the bezel on each display: the gap between two neighbours is the sum of their two facing frames.

Mixed sizes and resolutions

Size the image for the sharpest display. Every display gets its own slice, rendered at its own resolution, so a 4K display and a 1080p display beside it share one photograph and each keeps its own pixels.

A portrait screen

Rotate the display in System Settings and arrange it beside the others. It takes a taller slice of the same photograph, so choose an image tall enough to stretch over the portrait screen as well as wide enough to spread across the row.

Monitors stacked vertically

Arrange them one above the other. The image now needs height: two 4K monitors stacked want 4320 pixels tall. The vertical bezel is the one to set, because the frames that matter are the top and bottom edges.

A laptop beside an external display

Place the laptop in the arrangement where it sits on the desk, including how much lower its screen is. SpreadPaper reads that offset and slices to match. Bezels are set per display, so give the laptop its own value.

Getting the join right across the bezels

The housings of two monitors sit between their panels, and the picture has to carry on behind them the way a view carries on behind a window frame. Without compensation a horizon steps as it crosses the join and a road kinks.

Bezel compensation leaves out the strip of image that would fall behind the frames. The value is in points, the same units as the display arrangement. Set it by eye: raise it until a long straight line crosses the seam intact. On a pair of 27 inch 1440p monitors that usually lands near 70.

The bezel compensation guide goes through what to measure, how to check the result, and why the gap is not the same as the frame you can see.

Doing it by hand

You can do it in an image editor. Scale the photograph to the arrangement, cut one file per display, and set each file as that display's wallpaper in System Settings.

For each display, the slice is the part of the image over that display's rectangle in the arrangement, with the bezel strips left out, exported at the display's own native resolution. Nudging the photograph, moving a monitor or plugging in a laptop means cutting every slice again.

Fixing a soft image or a step at the seam

The wallpaper looks soft: Use an image at least as wide as the table above gives for your setup.
A horizon steps up or down at the seam: Raise the bezel value until the line runs through unbroken.
The picture is offset between displays at different heights: Match the arrangement in System Settings to how the displays sit on the desk, then reapply.

Where to go next: bezel compensation is the detail behind the step that does most of the work. Help walks the first launch warning through in three steps. The guides have the rest.