Merge Images Horizontally
Merge Images Horizontally places selected images in browser selection order without scaling, alignment controls, spacing, or background fill. Output width is the sum of widths and height is the tallest image; shorter images start at the top, leaving transparent space below. Each input is limited to 40 megapixels, but combined canvas dimensions can still strain memory.
Runs locally — files stay on your deviceAre images resized to the same height?
No. Original decoded dimensions are retained and top-aligned.
Horizontal concatenation creates one wider pixel canvas
Each image receives an x offset equal to the combined width of earlier images. Empty regions remain transparent in the PNG.
How it works
Select multiple images. Up to the first eight are decoded, output dimensions are calculated, each bitmap is drawn at the next x offset, and PNG is downloaded.
Key concepts
Selection order controls layout
The first selected file appears leftmost.
Tallest image sets height
Others leave transparent lower regions.
When to use it
- Create a quick side-by-side comparison.
- Join equally sized panels.
- Build a simple horizontal strip.
When not to use it
- Do not expect automatic equalization.
- Do not create huge panoramas without memory awareness.
- Do not expect spacing, captions, borders, or reorder controls.
Worked examples
Equal screenshots
- Input
Two 800×600 images- Expected output
1600×600 PNG
They align cleanly.
Different heights
- Input
800×600 and 800×400- Expected output
1600×600 with transparent area
Both begin at y=0.
Ten files
- Input
10 selected- Expected output
First 8 only
The implementation slices the list.
Common mistakes
Expecting all selected files
Only eight are processed. Correction: Merge in batches.
Assuming vertical centering
Images are top-aligned. Correction: Pre-pad or resize externally.
Underestimating canvas memory
Decoded RGBA and output can be large. Correction: Resize sources first.
Best practices
- Use matching heights.
- Select files in intended order.
- Estimate combined width before processing.
Related operations and differences
Merge Images Vertically
Choose Merge Images Vertically when you need to stack up to eight images vertically.; use Merge Images Horizontally specifically for merge horizontal.
Add Text Watermark to Image
Choose Add Text Watermark to Image when you need to place a text watermark in the lower-right corner.; use Merge Images Horizontally specifically for merge horizontal.
Adjust Image Brightness
Choose Adjust Image Brightness when you need to increase or decrease image brightness.; use Merge Images Horizontally specifically for merge horizontal.
Adjust Image Contrast
Choose Adjust Image Contrast when you need to increase or decrease image contrast.; use Merge Images Horizontally specifically for merge horizontal.
Adjust Image Saturation
Choose Adjust Image Saturation when you need to control the intensity of image colors.; use Merge Images Horizontally specifically for merge horizontal.
Crop Image
Choose Crop Image when you need to crop an image to an exact local pixel rectangle.; use Merge Images Horizontally specifically for merge horizontal.
Limitations and privacy
- First eight images only.
- No scaling, reorder UI, centering, spacing, captions, borders, background, or memory estimate.
- 40 MP applies per input, not total canvas.
Selected images are decoded and processed locally in this browser.
Frequently asked questions
How many images are supported?
Up to the first eight.
Are heights normalized?
No.
What alignment is used?
Top alignment.
Is output PNG?
Yes.