Merge images into one PDF

Getting the order right

Order is where merging usually goes wrong. Built-in tools follow an order you cannot see while you work: Finder on a Mac uses the order in which you clicked the files, the Windows print dialog uses the folder’s sort order, and in an Apple Community thread that 68 people marked as having the same problem, the iPhone Files app put a 200 image PDF out of order. Here the thumbnails show the final order before anything is saved.

Sort by name reads numbers the way people do, so IMG_9 comes before IMG_10, and phone cameras number photos in the order they were taken. For a long set, renaming the files 01, 02, 03 before you add them lets one click put everything in place.

Two or four images on one page

Under Images per page, 2 images puts two images on each A4 or Letter page, and 4 images makes a grid of two rows. The heading above the thumbnails then shows the images and the pages they fill, for example 6 images on 3 pages.

With Orientation on Auto, the tool picks the direction that shows your images larger and uses it for every page. Two landscape photos stack on a portrait page, top then bottom, and two portrait photos sit side by side on a landscape page, left then right. Choose Portrait to always stack them, or Landscape to always put them side by side.

Each image is fitted inside an equal share of the page and centered, so nothing is cropped. With the Small margin, a share is about 197 x 139 mm on A4 or 8 x 5.1 inches on Letter at 2 per page, and about 95 x 139 mm or 3.9 x 5.1 inches at 4 per page, the other way around on a landscape page. Every image keeps its own shape, so two photos of different shapes come out at different sizes: crop them to the same shape first if they should match. With an odd number of images at 2 per page, the last one takes the top half of the last page, or the left half of a landscape page, and the other half stays blank.

This page starts with the Small margin, about 6 mm, so the outer edges are not lost if your printer cannot print to the edge of the paper, and about 6 mm is left between images as room to cut. For a PDF you will only read on screen, pick None under Margin. The margin stays as you leave it when you switch between 1, 2 and 4 images.

The everyday case is an ID card, with the front and back on one page, as many forms ask. In our test on 15 October 2026, two 1,600 pixel wide photos of a sample card filled the two halves of one A4 page at about 205 DPI. The PDF was 352 KB with Best quality, and 98 KB with a 100 KB limit, with the card text still sharp. For a card cropped to its corners and printed at its real size, use ID card front and back on one page.

Four is the most images this tool puts on one PDF page. For more than four on one page, combine them into one picture first, in a row, a stack or a grid of up to nine, then add that picture here with 1 image per page. For one image file rather than a PDF, the combine tool on its own is enough.

What merging does to file size

With Best quality, JPG photos are copied into the PDF as they are, minus hidden extras such as location. In our test, at one image to a page, ten 12 megapixel JPG photos weighing 11.06 MB together became an 11.07 MB PDF: the PDF structure added about half a kilobyte per page.

Other formats can change size. PNG, GIF and BMP images are stored without loss. WebP, AVIF and HEIC photos cannot sit in a PDF as they are, so they become a high-quality JPG, which grows them: on 15 October 2026 a 79 KB WebP photo became a 178 KB page and a 56 KB AVIF photo a 158 KB page.

So a merged PDF of JPG photos is about as big as the photos added up. If that is too much for email, Smaller file brought the same ten photos down to 1.96 MB, about 200 KB a photo. For an exact cap, the PDF under 1 MB and under 300 KB pages are set up for that.

Built-in ways to merge images, and their limits

Most computers can already merge images into a PDF without another app. Here is how, and what to watch for:

If one of those already does what you need, use it. This page helps when the order matters, when pages need turning, when two images should share a page, or when the same steps should work on every device.