How to Convert Images to PDF: Page Size, Fit and Quality
Turn photos, scans or screenshots into one tidy PDF: pick the right page size, avoid cropped edges, and keep text sharp without creating a huge file.
By the PDF Logic team at Appzotech
Published Updated 8 min read
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What happens when images become a PDF
Each image becomes one page. That sounds trivial, but it hides the decision behind most problems: an image is measured in pixels, and a PDF page is measured in inches or millimeters. Something has to decide how many pixels go into each inch. That choice sets the page size, how sharp the page looks in print, and whether an upload form accepts it.
It also explains a common surprise: converting to PDF doesn’t make files smaller by itself. A PDF is a container. Put ten 4 MB photos in at full quality and the PDF will be at least as big as the ten photos together. The size only drops if you ask for the images to be reduced on the way in.
Get the images ready first
- Photographing paper? Lay the page flat in even light and fill the frame. Better still, use Scan to PDF, which suggests the page edges, straightens the perspective, lets you adjust brightness and contrast, and can make the text searchable.
- Name files in page order. “01-cover.jpg, 02-form.jpg” lets you sort the whole set in one click.
- Check the format. JPG to PDF takes JPG, PNG, WebP and single-page TIFF. The tool cannot open a TIFF in your browser, so it asks before uploading one to our server, which prepares that page. iPhone photos saved as HEIC need converting first, and Convert to JPG does that in your browser.
Convert images to PDF, step by step
- Open JPG to PDF and select Choose images, or drop the files onto the page. You can add up to 100 images, 50 MB each and 100 MB in total. Your browser draws the previews and builds the PDF, so the images are not uploaded.
- Put the pages in order. Drag them in the Your pages list, use Sort to arrange them by name, or nudge one page with Earlier and Later under the preview.
- Fix individual pages with Rotate, Crop, Replace or the remove button.
- Under PDF settings, choose a Paper size and an Orientation.
- Choose an Image fit and set the Margins.
- Choose an Output quality.
- Select Create PDF, give the file a name, and choose Download PDF. Change settings takes you back if something looks off.
The next three sections explain the choices in steps 4 to 6, because they decide how the PDF turns out.
Choose the paper size
Scroll the table to compare all columns.
| Setting | The page becomes | Use it for |
|---|---|---|
| Image size | Exactly the shape of each image, with no borders | Photos, screenshots, slides and anything read on a screen |
| A4 | 210 × 297 mm | Documents for most of the world |
| US Letter | 8.5 × 11 in | Documents for the United States and Canada |
| US Legal | 8.5 × 14 in | Long-form legal pages |
With a fixed paper size, leaving Orientation on Auto turns each page to match its image, so a landscape photo gets a landscape page. If you aren’t sure which paper size a recipient expects, A4 vs US Letter explains the difference.
Image size needs one more piece of information: the resolution. Use image DPI reads the pixels-per-inch value stored in the file and falls back to 72 when there isn’t one. A scanner writes a true value, so a 300 DPI scan of an A4 sheet (2480 × 3508 pixels) comes out as an A4 page. Phone cameras usually write 72 as a placeholder, which turns a 3024 × 4032 pixel photo into a page 42 inches wide and 56 inches tall. It looks normal on screen because viewers zoom to fit, but it prints as a poster, and an upload form that checks page size may reject it.
Converting phone photos of documents? Choose A4 or US Letter instead of Image size. You get a standard page whatever resolution the photo claims to have.
Fit the whole image or fill the page?
A photo and a sheet of paper are rarely the same shape, so on a fixed paper size something has to give.
- Fit whole image scales the image until it fits inside the page. Every edge stays visible, and you get white bands on two sides where the shapes differ.
- Fill page scales the image until it covers the page. There are no bands, and whatever overflows is cut off. When that happens, position sliders appear under the preview so you can choose which part to keep.
Use Fit whole image for anything with content near the edges: forms, receipts, ID cards, signed pages. Use Fill page for photos where a clean, borderless page matters more than the outer few millimeters.
Margins add white space inside the page edge, from 0 to 50 mm. Most office printers can’t print right to the edge of the paper, so 5 or 10 mm is a safe choice for pages that will be printed.
Pick the output quality
Scroll the table to compare all columns.
| Preset | What it does | Use it for |
|---|---|---|
| Preserve quality | Keeps every pixel. A JPG that doesn’t need rotating or cropping goes into the PDF untouched | Printing, archiving, small text |
| Balanced | Shrinks each image to at most 2,000 pixels on its longer side and saves it as a JPEG at quality 85 | Email and most uploads |
| Smaller file | Shrinks each image to at most 1,200 pixels on its longer side, at JPEG quality 70 | Tight upload limits |
To put those numbers in context: on an A4 page, 2,000 pixels on the long side works out to roughly 170 pixels per inch, which is comfortable on screen and acceptable in print. At 1,200 pixels it is roughly 100 per inch, fine on a phone but visibly soft when small print goes on paper. The page dimensions don’t change between presets, only the detail inside them.
The result screen shows the PDF’s size next to the combined size of your original images, so you can see what a preset saved before you download. No setting can add detail that wasn’t captured: a blurry photo makes a blurry page.
Fix common problems
- A page is sideways. Select it and choose Rotate. Each click turns it a quarter turn clockwise.
- Edges are cut off. You are on Fill page. Switch to Fit whole image, or move the crop sliders.
- The PDF is too big to send. Go back with Change settings and try Balanced, then Smaller file. To go further, run the result through Compress PDF.
- Text looks soft. Zoom the original image to 100%. If it is soft there, retake the photo closer and in better light. If the original is sharp, move up to Preserve quality.
- An image is refused. Animated images, multi-page TIFFs, JPEG photos over 120 megapixels and other images over 40 megapixels aren’t accepted. Export a single frame or a smaller copy and add it again.
- The page size is wrong for an upload. Open Page details under the preview to see each page’s dimensions in millimeters and inches, then switch to the paper size the form asks for. Troubleshooting a rejected PDF upload covers the other usual causes.
Check the PDF, then take it further
Open the downloaded file and look at three things: the page count and order, one page zoomed to 100% to judge sharpness, and the file size against any limit you have to meet. If the PDF is for a form or portal, confirm the page size in your reader’s document properties.
From there, OCR PDF makes photographed text searchable and copyable (how OCR works explains what to expect), Merge PDF adds the new pages to an existing document, and Organize PDF reorders pages later without rebuilding the file. The print dialog on Windows and macOS can also save selected images as a PDF, with less control over order, margins and size.
Frequently asked questions
Does converting an image to PDF reduce its quality?
Not with Preserve quality. A JPG that doesn’t need rotating or cropping is placed in the PDF as it is, and PNG, WebP and TIFF images are stored without lossy compression. Balanced and Smaller file trade detail for size on purpose.
Can I mix JPG, PNG and WebP in one PDF?
Yes. Add them together and arrange them in any order. Each image gets its own page, and with Orientation on Auto each page turns to suit its image.
What resolution do I need for printing?
Aim for about 300 pixels per inch at the printed size, which means about 2,500 pixels across the short side of an A4 or Letter page. Half that is still readable for ordinary text. With a fixed paper size, Page details under the preview shows the effective DPI of each image on its page.
Are my images uploaded?
No. JPG to PDF draws the previews and builds the PDF in your browser, so your images stay on your device. One exception is an image your browser cannot open, most often a TIFF. The tool asks first, and if you agree, only that image is uploaded so our server can prepare its page; we don’t keep it once the job is done. If you only need to change an image’s format, Convert to JPG also works without uploading.
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