JPG to PDF

What the JPG to PDF does

When you need photos, screenshots or scanned receipts as one document to email, print or file, this tool puts them into a single PDF. Add your images in the order you want and each becomes its own page.

The pages match the source. Each page is built to its image's exact dimensions, so nothing is stretched, cropped or letterboxed, and a JPEG's existing compression goes straight into the PDF without being applied a second time. PNGs are embedded losslessly, which suits screenshots and graphics with sharp edges.

How it works

Your images are read into memory and passed to pdf-lib, which detects the type. JPEGs go through embedJpg and PNGs through embedPng, and each image becomes an embedded object in a new PDF.

A page is then added at the image's pixel width and height, and the image is drawn to fill it. When every image is placed, pdf-lib writes the document and images.pdf downloads.

Processing pipeline

1. Step 1. Add one or more JPG or PNG images. They are read on your device and never uploaded.
2. Step 2. Arrange them; each image becomes a page in that order.
3. Step 3. pdf-lib embeds each image: JPEGs without re-encoding, PNGs losslessly.
4. Step 4. A page is created at the image's exact pixel size and the image fills it.
5. Step 5. The combined file downloads as images.pdf.

Privacy

Your images stay on your device. They are read from disk, embedded in the page's memory and turned into a PDF locally. Nothing is uploaded and no server keeps a copy.

There is no sign-in and nothing is saved. Close the tab and the images and the PDF are cleared from memory, so you can use it for IDs, receipts and personal photos.

Technical details

Standards and references

• ISO 32000 (PDF): defines the page coordinate system in points, where 1 point = 1/72 inch. The tool maps one image pixel to one point.
• ISO/IEC 10918 (JPEG): the JPEG standard. The already-compressed data is embedded directly, so JPEG pages are not recompressed.
• pdf-lib: embeds the images (embedJpg / embedPng) and writes the PDF in the browser.

Accuracy and limits

Each page is made at the image's pixel dimensions counted as points, and a PDF point is 1/72 inch. A 1200-pixel-wide image therefore gives a page about 16.7 inches wide (1200 ÷ 72). The aspect ratio is exact and the image fills the page, but the page's nominal paper size can be large because pixels are treated as 72-dpi points. Most viewers scale the page to fit the screen, so this rarely matters on screen. For printing you may need a fit-to-page option.

JPEGs are embedded without re-encoding, so converting adds no second round of JPEG loss; the picture in the PDF is the same data as your file. PNGs are stored losslessly, which keeps screenshots sharp but can make those pages larger than a JPEG would be.

There is no automatic fit-to-A4, margin or rotation step. If every page has to be Letter or A4 with even borders, use a different tool; this one keeps each page true to its image.

Everything runs in your browser's memory, so a big batch of high-resolution photos can be heavy for a phone or older laptop. If it stalls, convert in smaller groups.

Real-world uses

When it fits, and when it doesn't

For a uniform paper size with margins, use an image-to-PDF tool built around page layout. To make the result smaller, resize or compress the images first, then convert.

Frequently asked questions

References

• pdf-lib — Create and modify PDF documents in any JavaScript environment (GitHub)
• PDFDocument.embedJpg / embedPng — pdf-lib API reference
• Converting pixels and inches to PostScript points (Foxit)
• img2pdf — losslessly convert images to PDF (GitHub)
• ISO 32000-1:2008 — Portable document format (ISO)

Related tools