The Complete Guide to Converting JPG Images to PDF
Quality control, fit vs fill, page-range filtering, per-image rotation, and the privacy model.
1. Quality control and file size
The Quality slider re-encodes each JPG or WebP source at the chosen JPEG quality before embedding it in the PDF — that is what actually reduces the output file size, because jsPDF would otherwise embed the source bytes verbatim. The practical sweet spot is 80–90%: visually indistinguishable from 100% but 30–60% smaller. PNG sources are re-encoded as PNG (lossless) by default; drop below 100% and they are re-encoded as JPEG for size, which trades transparency and pixel-perfect edges for a much smaller file — the right call for photographs, the wrong call for screenshots and diagrams.
2. Fit vs Fill: per-page layout
Fit preserves the image’s aspect ratio and centres it on the page with whitespace around it — the whole image is always visible. Use it when the image is the entire content and cropping would lose information (receipts, documents, diagrams). Fill scales the image to cover the entire page, cropping the overflow — no whitespace, but parts of the image are lost. Use it for cover pages and full-bleed photography where a clean edge-to-edge look matters more than completeness.
3. Page-range filtering
When you upload a batch of images but only want a subset in the final PDF, the Page range box lets you include only the images you specify without deleting the others from the working set. Typing 1-3, 5 produces a 4-page PDF from images 1, 2, 3, and 5 (in that upload order). This is especially useful when you are assembling a document from a larger pool of candidates and want to try different subsets quickly.
4. Per-image rotation
Each image row has a rotation button that rotates that image 90° clockwise. The rotation is applied during re-encode so the embedded bytes are correctly oriented — not a metadata flag that some PDF viewers and downstream tools ignore. Press the button up to three times to reach 180° or 270°. This is the right fix when your phone stored a portrait photo with landscape orientation metadata, or when you need every image in a batch to share the same upright orientation.
5. Page sizes and orientation
A4 (210 × 297 mm) is the international standard for documents that will be printed in Europe, Asia, or Oceania. Letter (8.5 × 11 in) is the U.S. and Canadian standard for tax forms, school submissions, and government paperwork. Fit to Imagesizes each page exactly to the image it contains — no whitespace, no cropping, ideal for photo books and portfolios where the image is the entire page. Orientation (Auto / Portrait / Landscape) only applies to A4 and Letter; Fit to Image ignores it because the page takes the image’s own dimensions.
6. Privacy: browser-based, by construction
Every step runs locally inside your browser tab using the open-source jsPDF library and the HTML5 canvas. Your images are read by JavaScript, re-encoded on a local canvas, and written into the PDF structure — all on your own CPU. The bytes never touch a network. When you close the tab, everything is cleared from memory. This is why the tool can honestly claim 100% privacy, and why it works offline — important for ID documents, medical records, legal evidence, and confidential business paperwork.
7. Tips for the cleanest output
- Sort before you upload if you have many images — prefix filenames with numbers (01-, 02-) so they arrive in the right order automatically.
- Use 85–90% JPEG quality for photographs — visually identical to 100% at a fraction of the bytes.
- Keep PNG for screenshots and text — sharp edges, transparency, and lossless compression. This tool re-encodes PNG as PNG by default.
- Set a 10 mm margin if the PDF will be printed, so nothing is lost at the paper edge.
- Pick Fill for cover pages and Fit for documents — matches the visual intent of each page.
- Keep batches under 30 images for the fastest processing and smallest file size.
Conclusion
JPG-to-PDF is the everyday task of bundling photos, scans, or screenshots into one shareable document — and the cleanest way to do it is in the browser. Choose quality to balance size against fidelity, Fit or Fill to match the visual intent of each page, page-range filtering to include only what matters, and per-image rotation so every page is upright. With nothing uploaded and everything processed on your device, this tool turns a folder of images into a single, well-structured PDF in seconds.