How to Combine Two Photos into One JPG (4 Quick Ways)

Most "combine two photos" tutorials start with "download this app." I spent 20 minutes last week installing a collage app on my phone that turned out to plaster its logo across the bottom of every output. The app before that one required a $4.99/week subscription to export without a watermark. The one before that compressed my 12 MP photos down to 800x600.

The fastest method takes about 8 seconds and needs zero installations. But the right method depends on whether you want side-by-side or stacked, and whether you are on a phone or a computer.

Side by side vs top to bottom - picking the right layout

The layout choice is not aesthetic preference. It is dictated by what the two photos contain.

Horizontal (side by side) works when both images share a similar height. Before-and-after shots of a room renovation. Product comparison where you want a customer to see both options at a glance. Two headshots for a "meet the team" section. The viewer's eye scans left to right naturally, so the comparison feels instant.

Vertical (stacked) works better for tall, narrow content. Two phone screenshots that you need in a single file for a bug report. Scanned pages of a document. Chat conversation fragments. Stacking preserves the full width of each screenshot, while side-by-side would shrink them to half width and make the text unreadable.

Grid (2x2) is the odd one out. It only makes sense when you have exactly 4 images and want a compact square output - real estate listings, product color variants, a collage for social media. For just two photos, grid wastes two cells with blank space or forces the tool to duplicate your images.

I default to horizontal for photos and vertical for screenshots. That rule has held up for every use case I have encountered in 3 years of using merge tools daily.

Method 1: Browser tool (fastest for a one-off)

A browser-based tool runs the entire merge inside your browser using the Canvas API. No files get uploaded to a server. You select two images, pick a layout, and download the combined JPG.

Step-by-step with JPG Joiner:

1. Open jpgjoiner.com in any browser.
2. Drop both photos onto the upload area (or click to browse). You can also paste from your clipboard with Ctrl+V / Cmd+V - useful when you just took a screenshot.
3. Choose horizontal or vertical layout from the options panel.
4. Adjust spacing if you want a gap between the two photos (default is 0 px, which places them flush).
5. Click Download. The combined JPG saves to your downloads folder.

I timed this with two 4032x3024 iPhone photos (4.2 MB each). From dropping the files to having the merged JPG on my desktop: 8 seconds. About 3 seconds of that was the file picker dialog. The actual canvas rendering took under 1 second on a 2020 MacBook Air.

The clipboard paste shortcut is the part most people miss. If you take a screenshot on your Mac (Cmd+Shift+4), the image goes to your clipboard. Switch to the browser, click the upload area, and press Cmd+V. No need to find the file in Finder. On Windows, the Print Screen key plus Ctrl+V does the same thing.

Where this fails: if both photos are 12 MP or larger and your device has under 4 GB of RAM. Two 4032x3024 images each consume 48 MB as uncompressed bitmaps (width x height x 4 bytes), plus the output canvas needs another 48-96 MB depending on layout. That is 144-192 MB for just two photos - not a problem on any modern desktop, but tight on older phones.

Method 2: iPhone and Android shortcuts

iOS: the Shortcuts app approach

Apple's Shortcuts app (pre-installed since iOS 13) has a "Combine Images" action that merges photos without any third-party app. Most people do not know it exists because Shortcuts is one of those apps that sits in a folder labeled "Utilities" and never gets opened.

1. Open the Shortcuts app and tap the + button to create a new shortcut.
2. Add the "Select Photos" action. Set "Select Multiple" to on.
3. Add the "Combine Images" action. Set the mode to "Horizontally" or "Vertically."
4. Add the "Save to Photo Album" action.
5. Tap Done and run the shortcut. Pick your two photos, and the merged result appears in your camera roll within 2-3 seconds.

The output defaults to full resolution with no compression. On an iPhone 15 Pro, two 48 MP ProRAW photos merged vertically produced a 28 MB JPG. The shortcut ran in 1.8 seconds. You can add this shortcut to your home screen for one-tap access.

One caveat: the Shortcuts Combine Images action does not let you add spacing or a background color between photos. They get placed flush against each other. If you need a white border between them, you would need to chain additional Shortcuts actions (Resize, Overlay) that make the workflow fragile. For anything beyond a basic join, the browser tool is less hassle.

Android: Google Photos collage

Google Photos includes a collage feature that combines multiple photos. Open Google Photos, select two images, tap the + button, and choose Collage. Google generates a layout automatically.

The problem is that Google Photos forces a square output regardless of your input images. Two landscape photos get cropped to fit a square frame, chopping off the left and right edges. Two portrait photos lose the top and bottom. You have no control over the output aspect ratio, the spacing, or the background color.

For a quick social media post where the crop does not matter, this works in 5 seconds. For anything where you need the full image preserved - document scans, product photos, before-and-after comparisons - the cropping is a dealbreaker. Use the browser tool on your phone instead.

Method 3: Desktop apps

Preview on Mac

Preview is already installed on every Mac and can combine two photos, though the process is not obvious. Open the first image, go to Tools > Adjust Size, double the width (e.g., 4032 becomes 8064), uncheck "Scale proportionally." Undo to restore the image while keeping the larger canvas. Open the second image, Select All, Copy, then Paste into the first image and drag it to the right side. Export as JPG.

This is clunky. There is no snap-to-edge, no alignment guide, and no spacing control. I consistently end up with a 1-2 px gap or overlap that I only notice after exporting. It works for a one-off when you have no internet, but the browser tool is faster and more precise.

Paint on Windows

The classic MS Paint approach works similarly. Open the first image, drag the canvas handle on the right edge to make room, then paste the second image and drag it into position. Paint has been handling this since Windows 95.

The positioning is eyeballed, not pixel-perfect. Paint does not show coordinates while dragging, so getting two images flush against each other requires zooming in and nudging. For a quick internal email attachment, nobody will notice. For a client deliverable, use something more precise.

Paint also re-encodes at a fixed quality level that you cannot control. The output is typically around 85% JPG quality, which is visible on high-contrast edges like text on white backgrounds. Black text develops a faint halo of compression artifacts that was not present in the original.

Method 4: Command line one-liner

If you have ImageMagick installed (Homebrew on Mac: brew install imagemagick, apt on Ubuntu: sudo apt install imagemagick), combining two photos is a single command.

Horizontal (side by side):

convert img1.jpg img2.jpg +append side-by-side.jpg

Vertical (stacked):

convert img1.jpg img2.jpg -append stacked.jpg

With a 10 px white gap between the two images:

convert img1.jpg img2.jpg -splice 10x0 +append -chop 10x0 side-by-side.jpg

The +append flag means horizontal, -append means vertical. I mix these up about once a month. The mnemonic that finally stuck: the plus sign (+) looks like a horizontal crossbar, so +append is horizontal.

On two 4032x3024 photos, the +append command finishes in 0.4 seconds on an M1 Mac. The output defaults to 92% quality. To control quality explicitly:

convert img1.jpg img2.jpg +append -quality 95 side-by-side.jpg

The command line approach is overkill for a one-off. It shines when you do this repeatedly - add the command to a shell script or alias it in your .bashrc, and future merges take 2 seconds including typing the command.

Common problems when combining two photos

Mismatched image sizes

This is the number one problem I see people hit. One photo is 4000 px wide from a phone camera, the other is 800 px wide from a web download. Placed side by side, the small image occupies a tiny strip next to the large one. The output looks broken.

The fix is to resize the larger image down (or the smaller image up) before merging. In ImageMagick: convert img2.jpg -resize 4000x img2-resized.jpg scales the second image to match the width of the first. In a browser tool, some handle this automatically by scaling both images to equal height for horizontal layouts. Check the output preview before downloading.

Different aspect ratios

A 16:9 photo next to a 4:3 photo creates a jagged edge when placed side by side. The heights do not match, so one image extends below the other. The empty space gets filled with the background color, leaving a visible band.

Two options: crop one image to match the other's aspect ratio, or accept the background fill. For vertical stacking, mismatched widths cause the same problem on the sides. I crop rather than pad whenever possible - the background band makes the output look unfinished.

Color profile mismatch

Phone photos save in Display P3 color space. Screenshots and web-downloaded images use sRGB. When you merge a P3 photo with an sRGB screenshot, the Canvas API converts everything to sRGB. The photo's reds and greens shift slightly - not dramatically, but noticeably if the two images are side by side and you are comparing tones.

For most uses, this does not matter. For product photography or design mockups where color consistency matters, convert both images to sRGB before merging. On Mac: sips --matchTo '/System/Library/ColorSync/Profiles/sRGB Profile.icc' photo.jpg.

Output quality and file size

The file size of a merged JPG is not the sum of the two input files. JPG compression works on 8x8 pixel blocks, and the file header (Huffman tables, quantization matrices, EXIF metadata) is shared across the entire image. Two 4 MB photos merged at 92% quality produce roughly 6 MB of output, not 8 MB.

At 80% quality, the same merge drops to about 3.5 MB. The compression artifacts become visible on sharp edges - text, architectural lines, high-contrast boundaries - but are unnoticeable in organic textures like grass, skin, or fabric. For photos going to social media (which re-compresses everything to about 75% anyway), 80% is fine.

At 100% quality, you keep every pixel as-is, but the output balloons. Those same two 4 MB inputs produce a 12-14 MB merged file at 100% quality. That is too large for email (25 MB Gmail limit eats up fast when you have multiple attachments) and slow to load on web pages. The only reason to use 100% is archival or print production where you need every detail preserved for a future crop or enlargement.

My default is 92%. I have printed merged photos at 92% on an Epson P900 at 13x19 inches and could not distinguish them from the 100% version. The file size savings of 40-50% are worth it every time.