Merge Images

How images are aligned

Images are placed edge-to-edge in the order you added them — left to right for the horizontal layout, top to bottom for vertical. They're aligned to the top (horizontal) or left (vertical) rather than centered, so if your images are different heights or widths, the shorter or narrower ones leave a transparent gap rather than getting stretched or centered to match.

The result is always saved as a PNG, regardless of what format your source images were in — this preserves the transparent gaps mentioned above, which a JPEG (no transparency support) couldn't represent.

A worked example with sizes

Merge an 800 × 600 image with a 500 × 700 one. Side by side, the canvas is 1300 × 700 (widths added, tallest height), and the 800 × 600 picture leaves a 100-pixel transparent strip beneath it. Stacked, the canvas is 800 × 1300 (widest width, heights added), and the 500-pixel-wide picture leaves a 300-pixel transparent strip on its right.

Order, count and the file name

You need at least two images, otherwise the tool says to add at least two. Each drop adds to the list, the list numbers the pictures in the order they will appear, and Remove deletes a single entry. The result is a PNG named after the first image in the list, so photo1.jpg becomes photo1-merged.png.

Size and format considerations

Images are copied at their native size with no spacing, borders or resizing, so the canvas is the sum of the sizes in the merge direction. Five 3,000-pixel-wide photos side by side make a 15,000-pixel-wide PNG, which can be a big file. The combined width and height are checked before anything is drawn, against the same limit as the single-image tools: 16,384 pixels on a side and 268,435,456 pixels in total. Three 6,000-pixel-wide photos side by side would be 18,000 pixels wide, so that layout is refused with a message quoting the size and no download is made, while stacking the same photos is fine.