To fix an extra row or column in an Affinity sprite-sheet export on Mac, check the export rectangle’s position, dimensions, and output scale. Use a precisely sized slice for an already arranged sheet, then verify the exported PNG before changing the artwork.

This guide covers the current Affinity desktop interface and its Slice Studio. The task is to export an existing sprite grid at its intended pixel dimensions. Affinity’s current help documents custom export rectangles and individual slice outputs; the steps below use those controls directly.

Identify whether the extra pixel changes the file dimensions

First, separate two symptoms: a file that is one pixel too large, and a correctly sized file containing an unwanted edge pixel. They require different checks. Record the intended width and height, then open the exported file separately to check its dimensions and inspect the outermost rows and columns.

Use a simple expected-size calculation. For an illustrative sheet containing four 64 × 64 frames in one horizontal row, with no margins or gaps, the target is 256 × 64 pixels. A 256 × 65 export has a dimensional mismatch. A 256 × 64 export with an unwanted colored bottom row has the correct dimensions but needs its content or placement examined.

What you find Check first Useful next action
Width or height is one pixel too large Export bounds and their position Set an exact slice rectangle
Dimensions differ substantially Export scale and document DPI Check the slice’s actual output resolution
Dimensions are correct, but an edge looks wrong Artwork position and visible content Inspect the edge without resizing the sheet
The export contains unexpected artwork Slice type or export Area Choose the intended content boundary

Affinity distinguishes drawn slices from slices created from layers. A drawn slice includes all visible layers within its rectangle; a layer-derived slice includes only the content of its source layer. This distinction matters when a nearby object or background appears in the exported sheet. See Exporting using the Slice Studio.

Check pixel position as well as width and height

An integer width does not establish that a rectangle starts on a pixel boundary. In a geometric illustration, a 256-pixel-wide rectangle starting at X = 10.5 ends at X = 266.5. Both edges sit between pixel boundaries. That illustrates why checking width alone can miss an alignment problem; it is not a claim about Affinity’s exact rasterization formula.

For numeric inspection on Mac, open Window > General > Transform. The panel provides X, Y, W, and H, plus an anchor-point selector. Choose the top-left anchor when checking the top-left position of a rectangular export area. The measurements use the current ruler units and are relative to the ruler origin. These controls are documented in Transform panel.

If necessary, show rulers with View > Show > Rulers, then Control-click their intersection and choose pixels. If you previously moved the ruler origin, double-click the intersection to reset it before diagnosing coordinates. Affinity documents both actions in Rulers.

Inspect the export boundary’s position and size, rather than selecting all sprite artwork and rounding every value. For the illustrative four-frame sheet, the intended rectangle might be X = 0, Y = 0, W = 256, H = 64. Your existing sheet can start elsewhere; use the position that actually encloses its frame grid.

If the numeric display conceals small fractions, the Transform help identifies Settings > User Interface as the place to adjust decimal places. Increase the displayed precision while checking. Avoid changing artwork dimensions merely to make the numbers look tidy: a resize can alter frame content.

Use the correct pixel-alignment settings

Open View > Snapping and enable Force Pixel Alignment. Affinity documents that this snaps vector objects, nodes, handles, and pixel selection areas to whole pixels when they are created, moved, or modified. It also warns that snapping to an off-pixel object, guide, or grid can produce an off-pixel result, so temporarily disable conflicting snapping modes during correction. See Force Pixel Alignment.

For correcting an existing fractional position, leave Move By Whole Pixels off. That option constrains movement distance and can preserve an object’s fractional offset. For example, adding 10 to X = 10.5 produces X = 20.5. Affinity explicitly distinguishes this behavior from Force Pixel Alignment in the same pixel-alignment documentation.

Treat snapping as assistance during editing. After moving or adjusting the relevant boundary, check its numeric values again. Enabling a snapping option alone does not establish that every existing object has been corrected.

Export the arranged sheet through one exact slice

For an existing sheet, a custom drawn slice gives you a documented way to control the exported rectangle without making its dimensions depend on the changing extent of a sprite group. Affinity specifically recommends the Transform panel within Slice Studio for precise slice positioning and exact dimensions. See Exporting slices.

  1. Open Studio Manager, enable the Slice Studio entry if necessary, and switch to it. Enabling Studio entries is documented in Customizing Studios.
  2. Select the Slice Tool and drag a rectangle around the already arranged sheet. The tool is available by default in Slice Studio; its shortcut is S. See Slice Tool.
  3. With the drawn slice selected, use Transform to set its intended position, width, and height. For the illustrative sheet, use W = 256 px and H = 64 px, positioned over the four frames.
  4. Open Window > General > Slices, expand the slice entry, and choose PNG as its file format. Check its size scaling and displayed output resolution.
  5. Export the required size using that size’s export control, or leave only the intended slice checked and use Export Slices. Choose the destination folder and click Export.

The Slices panel documentation describes file-format selection, size scaling, and checked export entries. The separate Exporting slices instructions distinguish exporting one size, one format, or all checked slice outputs. For the first diagnostic export, choose one PNG output so the file you inspect is unambiguous.

Before exporting, check visible layers inside the rectangle. A drawn slice includes their content. If you instead create a slice from a group or layer, its initial bounds follow that item’s extent and its output contains only that source item. Use the slice type that matches the intended sheet, as explained in Exporting using the Slice Studio.

Preserve intentional empty space within each frame. In the four-frame example, each frame must retain its 64 × 64 allocation even if the graphic inside it is much smaller. Tightening the export to the visible artwork would change the grid you are trying to deliver.

Check DPI before assuming 1x means the expected pixels

Affinity documents a relationship between document DPI and Slice Studio’s 1x, 2x, and 3x sizes. Its example shows a 64 × 64 px document exporting at 64 × 64 at 1x when the document is 72 or 96 DPI. At 144 DPI, the documented 1x output is 32 × 32, and 2x produces 64 × 64. See the table in Exporting using the Slice Studio.

Check the resolution displayed on the slice and the dimensions of the resulting file. If scaling explains the mismatch, adjust the export setup before modifying frame sizes. Changing the sheet geometry to compensate for an export-scale setting makes the source harder to maintain.

Use the Export dialog when the sheet already fills one artboard

If the complete sheet occupies one artboard, you can use File > Export > Export, choose a PNG preset, and set Area to that named artboard. Inspect the preview and output dimensions, choose Ask for Location, then export and save. Show in Finder can reveal the destination afterward. These are the current Mac steps in Export dialog.

Choose the area deliberately. The current Export Settings documentation says that Whole document output from a document containing artboards produces separate image files for the artboards. Exporting several artboards this way does not assemble them into one sprite-sheet image. For one sheet, arrange the frames within a single intended rectangle and export that rectangle.

The Export dialog also allows alternative output width and height, with an aspect-ratio lock. Use those fields to verify the intended dimensions. Avoid forcing a 256 × 65 result to 256 × 64 as the first repair: changing output dimensions can resample the image rather than correct the original boundary. Affinity describes these size and resampling controls in Export Settings.

Respect the format and export limitations

PNG is a suitable choice when the sheet needs transparency; Affinity explicitly lists PNG transparency support in Supported file formats. If you deliberately enlarge hard-edged pixel artwork, Affinity describes Nearest Neighbor as the resampling option for hard-edge images. It is a scaling choice, not a repair for an incorrectly positioned export rectangle. See Export Settings.

Also check Include bleed where available. Affinity documents this option for PNG and says that enabling it includes the document’s configured bleed area. Leave it off when the required output is exactly the sprite-grid rectangle. The same documentation warns that an export exceeding a format’s maximum dimensions will be scaled to fit, with a warning in the Export dialog. See Export Settings.

The documented slice workflow exports defined areas; it does not provide instructions for automatic frame packing, animation timing, or general sprite-atlas metadata. In particular, Batch builder is documented specifically for Xcode JSON batches from Apple icon slices. For this task, the supported path is to arrange the frames yourself and export their shared rectangle, rather than use Batch builder as an atlas generator. See Slices panel.

Verify the corrected PNG before changing anything else

Open the new export separately and confirm three things: its exact pixel dimensions, the outermost rows and columns, and the frame boundaries. In the illustrative 256 × 64 sheet, vertical frame divisions should fall at 64, 128, and 192 pixels from the left edge. These values follow directly from the stated four-frame layout.

If the file is now the correct size but an unwanted pixel remains, inspect the visible source content at that location. If it is still one pixel too large, recheck the selected slice, its X/Y/W/H values, output scaling, and bleed setting. This sequence separates a boundary problem from a content problem without repeatedly resizing the artwork.

Keep the corrected export rectangle and export setup with the document. The useful result is a PNG whose dimensions and frame grid match your intended layout. Once both checks pass, there is no need to remove a row or column from the finished file by guesswork.

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