How to Convert Images to PDF Online: Page Sizes, Margins & Multi-Page Scanning
Learn PDF point geometry (72 DPI points), A4 vs. US Letter paper sizing, and how to assemble clean multi-page receipt and ID document PDFs.
Why Combining Photos into a Single PDF Beats Sending Loose Image Attachments
When submitting scanned university transcripts, multi-page signed contracts, expense receipts, CNIC/passport copies, or design portfolios by email or through an online portal, attaching 12 separate `.jpg` files in random filename order creates a headache for the reviewer. Many portals only provide a single file-upload slot that accepts `.pdf`.
The Image to PDF Converter lets you drop up to 30 `JPG`, `PNG`, or `WebP` images, reorder them visually, rotate sideways phone photos (`90°` steps), choose standard paper dimensions (`A4`, `US Letter`, `Legal`, or `Fit to Image`), set margins and background color, and compile a clean, single-file PDF in your browser using `pdf-lib`.
How to Combine Images into a PDF Document
- Drag and drop up to 30 images (`JPG`, `PNG`, or `WebP`, up to 20 MB each) into the upload box, or click 'Select Images'.
- Use the left/right arrow buttons or rotation button (`90°`) on each image card to put your pages in exact reading order and fix sideways camera shots.
- Configure your document layout in the settings panel: 'Page Size' (`A4`, `US Letter`, `Legal`, or `Fit to Image`), 'Orientation' (`Auto`, `Portrait`, or `Landscape`), 'Margins' (`None`, `Small 0.25"`, or `Normal 0.5"`), 'Image Fit' (`Contain` or `Cover`), and 'Quality'.
- Type a custom output filename (e.g., `application-documents.pdf`) and click 'Generate & Download PDF'.
PostScript / PDF Point Geometry (72 Points per Inch)
1 Inch = 72 PDF Points
A4 Page = 595.28 × 841.89 pts (210 × 297 mm)
US Letter = 612 × 792 pts (8.5 × 11.0 in) | Legal = 612 × 1008 pts (8.5 × 14.0 in)
Usable Area = (PageWidth - 2 × MarginPts) × (PageHeight - 2 × MarginPts)Under the ISO 32000-1 PDF specification, page coordinates are measured in PostScript user-space points (`1 pt = 1/72 inch`). Each uploaded image is normalized through an HTML5 `<canvas>` (handling WebP transcoding and user rotation) and embedded into a new `PDFDocument` via `pdf-lib`. In 'Contain (Full Image)' mode, the image is scaled by `Math.min(usableW / imgW, usableH / imgH)` and centered so no part of your scan is ever cropped.
Worked Examples: Document Scans, Receipt Packets, and Photo Books
Below are three real document assembly setups verified in the Image to PDF Converter.
Example 1: 6-Page University Transcript & ID Packet for Printing (A4, Small Margins)
Combining 6 phone photos of academic certificates into a standard printable A4 PDF.
6 JPG images | Page Size: A4 | Orientation: Portrait | Margins: Small (18 pt / 0.25 in) | Fit: ContainA 6-page `595.28 × 841.89 pt` A4 PDF with uniform 0.25-inch white borders around every certificate so printer rollers never clip the edges.Key takeaway: Choosing 'Small' (`18 pt`) or 'Normal' (`36 pt`) margins is essential when the recipient might print the PDF on a physical laser/inkjet printer.
Example 2: Mixed Portrait & Landscape Slides ('Auto' Orientation)
Merging 4 vertical phone receipts and 2 wide desktop screenshots into one report.
6 mixed-aspect PNG/JPG files | Page Size: A4 | Orientation: Auto (Match Image) | Fit: ContainPages 1–4 render as Portrait A4 (`595×842 pt`) and Pages 5–6 automatically flip to Landscape A4 (`842×595 pt`) so wide screenshots fill the page cleanly.Key takeaway: 'Auto (Match Image)' checks whether `image.width > image.height` on each individual page and rotates the page box accordingly.
Example 3: Edge-to-Edge Digital Portfolio ('Fit to Image', No Margins)
Creating a digital comic or design presentation where each PDF page matches the exact pixel aspect ratio of its artwork.
8 WebP illustrations | Page Size: Fit to Image | Margins: None (0 pt)An 8-page borderless PDF where each page's dimensions match the source artwork with zero whitespace bars.Key takeaway: 'Fit to Image' with 'None' margins eliminates letterbox bars when the PDF will only be viewed on screens.
Choosing Between A4, US Letter, and 'Fit to Image'
In Pakistan, the UK, Europe, the Middle East, Asia, and Australia, `A4` (`210 × 297 mm`) is the universal ISO 216 standard for office printers and official submissions. In the United States and Canada, `US Letter` (`8.5 × 11 inches`, which is 6 mm wider and 18 mm shorter than A4) is standard.
Always choose `Contain (Full Image)` when converting text documents, receipts, or ID cards—`Cover (Fill Page)` zooms in until the entire printable area is filled, which crops off the top/bottom or left/right edges if the camera aspect ratio (`4:3` or `16:9`) doesn't match the paper aspect ratio (`1 : √2` for A4).
Batch Limits, Compression Settings, and Cropping Warnings
- Avoid 'Cover (Fill Page)' on text documents: 'Cover' mode intentionally crops image edges to eliminate white margins. Use 'Contain (Full Image)' for any document containing text, signatures, or borders.
- WebP and rotated images: Because the PDF specification natively embeds JPEG (`DCTDecode`) and PNG (`FlateDecode`) streams rather than WebP, WebP uploads are automatically transcoded to high-clarity JPEG/PNG streams during PDF generation.
- Maximum batch size: Up to `30 images` (`20 MB` max per image) can be combined in a single run. If you have two separate 30-page PDFs, merge them afterward using our Complete PDF Toolkit.
When to Use a Different PDF or Image Utility
- Complete PDF Toolkit: Use when you already have `.pdf` files that you want to merge together, split by page range, rotate, or convert back into images.
- Image Compressor: Use when you want to shrink a single image file without wrapping it inside a PDF container.
- Image Format Converter: Use when converting between `PNG`, `JPG`, and `WebP` image formats.
Frequently Asked Questions About Converting Images to PDF
Can I combine JPG, PNG, and WebP images together in the same PDF?
Yes! You can mix `.jpg`, `.png`, and `.webp` files of any resolution in the same queue. The tool normalizes and embeds each image onto its own page in the order you arrange them.
How do I keep myPDF file size small when combining 15+ camera photos?
In the PDF Configuration panel, set 'Compression & Quality' to `Medium (75% - Smaller Size)` or `High (88% - Recommended)`. Using `Maximum (100% - Lossless)` embeds uncompressed PNG streams, which makes multi-page photo PDFs very large.
What is the difference between 'Contain (Full Image)' and 'Cover (Fill Page)'?
`Contain` scales the image so the entire photo fits inside the page margins without cutting anything off (adding neat margin space if the aspect ratio differs). `Cover` scales the image until it fills 100% of the page box, cropping the overhanging edges.
How do I fix a photo that was taken sideways on my phone before generating the PDF?
Click the circular rotate button on that specific image's thumbnail card in the queue. Each click rotates that page by `90°` clockwise (`0° -> 90° -> 180° -> 270°`), and the badge shows the active rotation angle.
How can I merge my newly created Image-to-PDF file with an existing PDF?
Download your generated PDF here, then open our Complete PDF Toolkit (`/tools/pdf-toolkit`) and drop both PDFs into the 'Merge PDFs' tab to combine them into a single document.