How to Merge Photos into One Image: Layouts, Sizes and Apps

Almost every request to combine pictures falls into one of four shapes. Side by side puts two to four images in a single row; it is the shape of a before-and-after, a product in two colors, or a then-and-now pair. Vertical stack runs images top to bottom and is how you turn five screenshots of a long chat, a receipt or a recipe into one tall picture that scrolls naturally on a phone. Grid fills rows and columns, 2 × 2 for four shots or 3 × 3 for nine, and is the classic collage. The fourth, less obvious shape is one long strip that you later cut into slides.

The strip is worth knowing because it is how continuous Instagram carousels are made. Three portrait slides of 1080 × 1350 px placed edge to edge form a 3240 × 1350 px canvas. You design or merge across that whole strip, so a panorama or a subject can cross the slide borders, and then cut it into three equal pieces with split image. When someone swipes, the picture continues from one slide to the next. Instagram raised the carousel limit from 10 to 20 slides in 2024, so a strip can be much longer than it used to be.

Choosing the shape first matters because it decides which edge every picture must share. A row needs one height, a stack needs one width, and a grid needs one cell size, which usually means one aspect ratio. It also decides how big the file gets: a row grows in width with every picture you add, a stack grows in height, and a grid grows in both. The cards below show the proportions of a typical result for each layout so you can picture the final canvas before you start.

Photos from different sources almost never share a size. An iPhone photo is 4032 × 3024 px, a screenshot from the same phone may be 1179 × 2556 px, and an image saved from a website might be 800 × 600 px. Put them next to each other untouched and you get a ragged edge, a tiny picture beside a huge one, and white or black bars filling the gaps. The fix is to scale every picture so the shared edge is equal: for a row, resize each image to the same height, for example 1080 px; for a stack, resize each to the same width, such as 1080 or 1179 px.

When the shapes differ too, scaling alone is not enough. A portrait and a landscape photo at the same height still have very different widths, which looks unbalanced in a before-and-after. Crop both to the same ratio first, 4:5 or 1:1 are safe choices, then match the size. Our guide on cropping an image to a ratio walks through choosing the ratio and keeping the subject centered. For plain scaling to an exact number of pixels, resize the image before you merge, or let the merge tool do it.

Always scale down toward the smallest picture rather than up toward the largest. Shrinking a 4032 px photo to 1080 px keeps it sharp; stretching a 600 px screenshot to 1080 px blurs every letter, and the soft picture stands out next to its crisp neighbors. On the merge images tool, Match sizes on Auto gives a row one height and a stack one width, and Smallest guarantees nothing is enlarged.

A gap, often called a gutter, is the empty space between pictures. Zero puts them edge to edge, which suits a carousel strip or a long screenshot where the join should vanish. A thin gap of 10–20 px on a 1080 px picture, roughly 1–2% of its width, reads as a deliberate line and makes a grid look tidy. Match the outer border to the gap so the edges feel even. The gap and border take the background color: white looks clean on most feeds, black suits dark photos and night shots, and a light grey such as #F2F2F2 softens a grid without looking like an empty page.

Output size is simple arithmetic, and it grows faster than people expect. Four 4032 px phone photos side by side make a picture over 16,000 px wide, far more than any screen shows and more than many apps will accept. For sharing in chat, email or social posts, keep the finished width at or under 4000 px; 2048 px is plenty for most phones, and 1080 px matches Instagram. Messaging apps recompress large images anyway, so a sensibly sized original survives their compression better than a giant one.

Format depends on what is in the pictures. Screenshots, charts and anything with text belong in PNG, which is lossless and keeps letters sharp. Photos belong in JPG at quality 80–85, which looks identical to the source at a fraction of the size. A tall PNG of photos can easily reach 20 MB or more, while the same stack as JPG is usually a few megabytes. Remember that JPG cannot hold transparency, so a transparent gap turns white, and that JPEG has a hard limit of 65,535 px on any side, which matters only for very long stacks.

The iPhone Photos app has no collage or merge feature, but the Shortcuts app does. Its Combine Images action joins any number of selected photos horizontally, vertically or in a grid, with a spacing value in pixels; a following Save to Photo Album action puts the result in your library. Shortcuts has been built into iOS since iOS 13 and came to the Mac with macOS Monterey in 2021, so the same shortcut works on both. On Android, Google Photos has a Collage option among its create tools, with ready-made templates for a handful of pictures, and Samsung Gallery has Create → Collage for two to six images.

Desktops need a little improvising. In Windows Paint you can enlarge the canvas, paste the second picture and drag it into place, which works for two images but makes exact alignment hard. PowerPoint is more precise: set a custom slide size, place the pictures with the alignment tools, then export the slide as a PNG or JPG. macOS Preview resizes images well under Tools → Adjust Size but cannot extend a canvas or join files, so on a Mac use the Shortcuts action, Keynote, or a browser tool. Canva and browser merge tools give exact control over gaps, background and output size.

Stitching screenshots is a vertical stack with one extra problem: overlap. When you scroll and capture again, the bottom of one shot usually repeats at the top of the next, so a plain stack shows the same message or line twice. Before merging, crop the repeated band off the top of each following screenshot, keeping one or two lines of context so the reader can follow the join. Android 12 and later can capture a scrolling screenshot directly with Capture more, and Safari on iPhone saves a Full Page capture as a PDF, but neither works in every app, so manual stitching is still the common route for chats and app screens.

Comparison images follow stricter rules than collages, because the viewer is judging a difference. Shoot or crop both pictures with the same framing, the same ratio and, ideally, the same light, then merge them side by side at the same height with a small gap or none. Put the before on the left, since people read left to right, and add labels only if the platform allows text on images. Marketplaces often restrict the main listing photo; Amazon, for example, asks for a single product on a pure white background, so comparison composites belong in the secondary image slots.

Phone photos carry EXIF metadata: the camera model, the date and time, and often the exact GPS coordinates of where each picture was taken. A merged image is a new file drawn on a fresh canvas, and most merge tools do not copy the source photos' EXIF into it, which is usually what you want before posting a collage of your home or a child's school. Do not assume it, though. Check the result in the file's Get Info or Properties panel, or on iPhone swipe up on the photo, and look for a location before you share it publicly.

Printing changes the target from pixels on screen to pixels per inch. Photo labs print at 300 dpi, so a 4 × 6 in print needs 1200 × 1800 px and a 5 × 7 in print needs 1500 × 2100 px. An A4 sheet at 300 dpi is 2480 × 3508 px and US Letter is 2550 × 3300 px. Build the collage at those dimensions, with a gap of 20–30 px so the photos do not visually touch, and leave a few millimeters of margin because labs trim the edges slightly.

Match the grid to the paper's ratio before you merge, because a print lab will otherwise crop or pad the image to fit the sheet. A 4 × 6 print is 2:3, so a grid of 2 columns and 3 rows of square photos fills it exactly, while a 3 × 3 grid of squares leaves bands at the top and bottom. If the collage is going to a portal or an email instead of a printer, reduce the image size in KB after merging, not before.

Most bad merges fail in one of a few predictable ways, and almost all of them trace back to skipping the size step. A row of photos with different heights forces the tool either to leave bars or to stretch something; an enlarged screenshot turns blurry; a stack saved in the wrong format becomes too heavy to send or attach. None of these need special software to fix, only a second pass with the right setting and a minute spent checking the result.

Check the finished image at 100% zoom before you share it, not just as a thumbnail. Look at the joins, the smallest text and the file size shown in your file manager. If the photo grid maker or any other tool produced something too large, lower the width rather than the JPG quality first, because halving the width cuts the file to roughly a quarter while keeping it sharp at normal viewing size. Lower the quality below 80 only if the width is already where you need it.