How to Convert Images to PDF

When a PDF Works Better Than Separate Images

Many upload forms accept only one file, and separate photos of a document leave the reader to guess their order. A PDF keeps the pages in sequence, opens in common PDF viewers and prints on standard paper, which helps with receipts, ID scans, photographed notes or a series of screenshots.

What the Tool Does With Your Images

Each image becomes one page. It is scaled to fit inside the margins with its proportions kept and is centred; small images are enlarged and large ones drawn smaller, but their pixel dimensions do not change. How the image data is stored depends on the format:

• JPG files are copied into the PDF unchanged, metadata included. They are not compressed a second time, and the PDF is about as large as the images together.
• PNG files are stored without lossy compression and usually keep their transparency. A PNG without an alpha channel adds about its own file size to the PDF, but one with an alpha channel, the way most transparent PNGs are saved, is stored uncompressed.
• WebP files are encoded again as JPG at quality 100, because PDF has no WebP support. They usually become much larger, and in our tests transparent areas turned black.

The PDF is put together in your browser by JavaScript (the jsPDF library); the tool does not send your images to LeedyBox. It downloads as converted_images.pdf, so rename it before you send it.

Step by Step

1. Open JPG to PDF and choose or drop your files in the "Choose Image Files or Drag & Drop Here" box. The file picker offers JPG, PNG and WebP.
2. Check the "Page" badges under "Selected Images". The first order depends on which file the browser finished reading first, not necessarily on the file names, so drag the cards into place.
3. "Add More Images" adds files at the end; the drop box is hidden once images are loaded, so use this button for further files. The × button removes one image and "Clear All" starts again.
4. Choose Page Orientation, Page Margin and Page Size. They apply to every page.
5. Click "Convert to PDF Document" and wait for the download.

Choosing Page Size, Orientation and Margins

The defaults are A4 (Standard), Auto (Matches Image) and No Margin (Fit Full Page). Auto makes a page landscape when the image is wider than it is tall, and portrait otherwise; Portrait and Landscape also work with US Letter, despite the "A4" in their labels. A4 is 210 × 297 mm and US Letter 215.9 × 279.4 mm. Small Margin keeps a 10 mm border free on every side and Big Margin 20 mm.

An example: a 4000 × 3000 photo on A4 with Auto and No Margin gets a landscape page and is drawn 280 × 210 mm, with 8.5 mm white strips left and right, because A4 (about 1.41 : 1) is longer than 4 : 3. Forced to Portrait with Small Margin, the same photo shrinks to 190 × 142.5 mm, less than half the sheet.

Fit to Image Size makes each page as large as its image at 96 pixels per inch: a 1920 × 1080 screenshot gives a page of 508 × 286 mm. That suits reading on screen, while printing it on A4 or Letter means scaling it down. A margin with this option shrinks the image inside the page instead of enlarging the page. Keep the orientation on Auto: Portrait with a landscape image, or Landscape with a portrait one, turns the page but not the image, so part of the image is cut off. jsPDF also caps a page at 200 inches (5,080 mm), so an image more than 19,200 pixels long or wide, such as a full-page capture of a long website, loses its end; cut it into parts with Crop Image first.

Will the Pages Print Sharply?

Sharpness on paper depends on the pixels per inch (PPI): pixels across divided by the printed width in inches (millimetres ÷ 25.4). About 300 PPI is a common target for photos viewed up close; text often stays readable at 150 to 200 PPI. A 4 : 3 image on A4 landscape without a margin is printed 280 mm (11.0 in) wide:

• 4000 × 3000 pixels: about 363 PPI.
• 1200 × 900 pixels: about 109 PPI, noticeably soft.
• 400 × 300 pixels: about 36 PPI, blurry or blocky.

Enlarging adds no detail, whether the tool does it or you do it beforehand. A full A4 page at 300 PPI needs about 2480 × 3508 pixels, so photograph documents at the camera's full resolution and fill the frame with the page. Resizing Images: Pixels, Aspect Ratio and DPI explains PPI in more detail.

Keeping the PDF Small

We ran the tool's conversion code, with jsPDF 2.5.1 (the version the page loads), on test images with A4, Auto and No Margin. Sizes use 1 KB = 1,000 bytes. Other images give other numbers, but the pattern follows from how each format is stored:

• A photo PDF follows the size of its JPGs, so shrink them first with the Image Compressor or the Image Resizer, keeping enough pixels for the print sizes above.
• A colour PNG with an alpha channel takes about 4 bytes per pixel in the PDF, roughly 48 MB for 12 megapixels, while the 256-colour palette version stays small. If a PDF made from PNGs is far larger than the files themselves, they probably have an alpha channel, which some programs add even when nothing is transparent. When you do not need the transparency, convert such PNGs to JPG first, and do the same with WebP images: in the Image Compressor set "Output format" to JPG, or use the Image Converter. Transparent areas become white.
• Still too large for an upload limit? Compress PDF renders each page again as a JPG at about 65 to 108 pixels per inch, depending on the level. That is often enough for reading on screen but soft in print, so check that small text stays readable.

Common Problems and Fixes

• A photo is sideways or distorted. Many phones store photos on their side with an orientation tag (EXIF) that tells viewers how to turn them. The thumbnails look upright because current browsers apply the tag, and the tool sizes the picture from these upright dimensions. It copies the JPG data unchanged, though, and PDF viewers generally ignore the tag, so the photo can appear sideways and squeezed into an upright frame. Run such photos through Rotate & Flip Image or the Image Compressor, which both apply the orientation and save a new copy with upright pixels, then convert again.
• White strips beside every photo. Crop the photos to the page shape with Crop Image: choose Custom, enter 210 and 297 for portrait A4 (297 and 210 for landscape, 8.5 and 11 for Letter) and press "Select all" for the largest area. A 3000 × 4000 photo becomes 2828 × 4000. Or use Fit to Image Size.
• Part of an image is missing. With Fit to Image Size, either Portrait or Landscape was chosen for an image of the other shape, or the image is more than 19,200 pixels long or wide. Choose Auto, or cut long images into parts.
• A page looks scrambled. In our tests, interlaced PNG files (an option some editors offer for web images) came out as garbled stripes or blocks unless they had an alpha channel: the tool passes their compressed data to the PDF as it is, and PDF does not support PNG interlacing. Convert such files to JPG first.
• A transparent PNG comes out blank or nearly blank. In our tests this happened with PNGs saved with a small palette of 16 colours or fewer plus transparency, as some PNG optimisers save simple graphics and as the Image Compressor does at its lowest PNG settings: the tool reads their transparency incorrectly. Use a full-colour version of the image if you have one, or convert it to JPG if it does not need transparency.
• An error message, or a page without its picture. The tool handles JPG, PNG and WebP. Damaged files and other formats dropped on the box, such as AVIF images or HEIC photos from iPhones, can stop the conversion with an error, in which case no PDF is downloaded, or produce a blank or garbled page. Convert such files to JPG before you add them.

Checking the PDF Before You Send It

Compare the page count with the number of images, scroll through to check order and orientation, and zoom in on the smallest text. In the print dialog, a "fit" option scales the whole page, margins included, to the printable area, while "actual size" keeps your measurements but can clip the edges of a page without margins.

JPG photos keep their EXIF metadata inside the PDF, including GPS coordinates if the phone recorded them, and anyone who extracts the images can read it. For a PDF you will share, clean the photos before converting them: Remove EXIF Data keeps the image data unchanged and, by default, the orientation tag, so it does not fix sideways photos. The Image Compressor and Rotate & Flip Image drop the metadata while they save new, re-compressed copies with upright pixels.

The pages are pictures, so their text cannot be searched or copied. To get the text, run the original images through Image to Text (OCR); Extracting Text From PDFs: Text Layers and OCR explains the difference between image and text PDFs and why recognised text needs checking. Keep the original images until you have checked the PDF.

Frequently Asked Questions