Image to PDF Converter

Page size reference

How it works

Each image becomes one page in the PDF. The tool reads your files locally using the browser File API, draws them onto an offscreen canvas to ensure correct colour-space rendering, then embeds the result in a PDF page using jsPDF — an open-source JavaScript PDF library. The entire pipeline runs in your tab; nothing is uploaded.

1. Add images — drag and drop or click to browse. Supported formats: JPEG, PNG, WebP.
2. Reorder — use the Up/Down buttons. Each image becomes one page, in list order.
3. Choose options — page size, orientation and how the image is fitted to the page.
4. Convert — click "Convert to PDF & Download". The PDF file is saved directly to your device.

Image fit modes explained

Tips for the best results

• JPEG for photos — JPEG files embed compactly in PDF, giving a much smaller download than PNG.
• PNG for graphics with sharp edges — logos and screenshots with text look sharper as PNG than as JPEG.
• Portrait for tall images, Landscape for wide images — matching the page orientation to the image avoids empty margins.
• Use Fit — this is the safest option for mixed-size images; each image is centred with equal margins.

A brief history of the PDF

The format you are creating began as a project called "Camelot", started by Adobe co-founder John Warnock in 1991. The goal was audacious for its time: a single file that would look identical on any computer, printer or screen, regardless of the software or fonts installed. Adobe released PDF 1.0 in 1993, building on the company's earlier PostScript page-description language. For its first 15 years PDF was a proprietary Adobe format; in 2008 it became an open international standard, ISO 32000-1, which is why today any program — including this one — can read and write PDFs freely.

What makes a PDF different from an image or a Word document is that it is a fixed-layout, self-contained page description. It embeds everything it needs — the fonts, the raster images, the vector graphics and their exact positions — so the page renders the same everywhere and cannot reflow or shift. That reliability is precisely why PDF became the universal format for anything that must look the same to everyone: contracts, forms, invoices, tickets and scanned documents.

How your images live inside the PDF

Inside a PDF, each picture is stored as an image XObject — a self-contained object recording the width, height, colour space and the compressed pixel data. The clever part is how that data is compressed, and it directly explains the JPEG-versus-PNG tip above. A JPEG is embedded using the DCTDecode filter, which means the already-compressed JPEG bytes are carried into the PDF essentially as-is — so a photo stays compact. A lossless image (like a PNG) is stored with the FlateDecode (zip) filter, which keeps every pixel but produces a much larger object. That is the underlying reason a PDF of photos is smallest when the sources are JPEGs, and why graphics with crisp text are sharper when kept lossless. A PDF is also an ordered set of independent pages, so the file can later be merged, split or reordered without re-rendering — each page stands on its own.

The quiet science of paper sizes

The page-size options are not arbitrary. The ISO 216 A-series (A4, A3 and friends) is built on a single elegant idea: every size shares the exact same shape, an aspect ratio of 1 : √2 (about 1 to 1.414). That ratio has a magic property — fold or cut a sheet in half across its long side and you get two sheets of the identical proportion, just one size smaller. The series is anchored by A0, which is exactly one square metre; halving it gives A1, halving that gives A2, and so on down to A4 at 210 × 297 mm. This is why scaling a document between A-sizes never distorts it and why two A4 pages tile perfectly onto one A3.

North America never adopted the metric system for paper, so its Letter (8.5 × 11 in = 215.9 × 279.4 mm), Legal (8.5 × 14 in) and Tabloid (11 × 17 in) sizes come from tradition rather than mathematics — their exact origins are genuinely murky, with one oft-repeated story tracing the 11-inch length to the span a paper-maker could comfortably reach across a mould. Practically, the choice is simple: use A4 almost everywhere in the world, and Letter in the United States and Canada, where printers default to it.

Pixels, points and DPI — why an image looks small or grainy

Here is the concept that trips most people up. An image's pixels are a fixed count, but how big — and how sharp — those pixels print depends entirely on an assumed resolution. PDF measures its pages in points, where one point is 1/72 of an inch. Screens are conventionally treated as 96 pixels per inch, while crisp printing wants about 300 dots per inch. Because one inch is 25.4 mm, you can map a pixel count to a physical size with simple arithmetic: millimetres = pixels × 25.4 ÷ DPI.

Take a 1000-pixel-wide image as an example:

• At 300 DPI it prints about 3.3 inches (~85 mm) wide — small, but sharp.
• At 96 DPI the same 1000 pixels spread to about 10.4 inches — much bigger, but the dots are coarser.
• Stretch those 1000 pixels across a full A4 page and they get enlarged beyond their native detail, which is when an image starts to look soft or pixelated.

The takeaway: if you need print-quality output, start with a high-resolution image. There simply aren't enough pixels in a small screenshot to fill a sheet of paper crisply, no matter how the page is sized.

The one caveat to know: it's a picture, not text

This is the most useful thing to understand about converting images to PDF. The result is an image-only PDF — the page is a photograph of your content, with no real text layer. That means the words in the picture are not selectable and not searchable; you cannot highlight a sentence, copy a phrase, or have Ctrl+F find anything, because to the PDF it is all pixels. Making a scanned-image PDF searchable requires OCR (Optical Character Recognition), a separate step that reads the picture and adds an invisible text layer behind it. For sharing a photo album, a receipt or a signed form this doesn't matter at all. But if you are digitising a document you'll want to read or search later, run it through an OCR tool afterwards.

A couple of related points round this out. For long-term archiving there is a dedicated sub-standard, PDF/A (ISO 19005), which requires a file to be fully self-contained — all fonts embedded, no encryption — so it will still open correctly decades from now. And remember that phone photos are stored in RGB (the colour model of screens and cameras); professional printing presses use CMYK ink, which has a smaller colour range, so vivid screen colours can shift when sent to a commercial printer. A simple image-to-PDF keeps everything in RGB, which is exactly right for on-screen use and office printing.

What people use image-to-PDF for

Turning images into a PDF is one of those quietly essential tasks, and the reasons are remarkably consistent:

• Submitting documents. Application portals, schools and government forms almost always demand a PDF, not a folder of JPEGs — so a passport photo, a signed form or a set of certificates needs to become one PDF.
• Phone scanning. Snapshots of a printed contract, a handwritten note or a whiteboard become a tidy, single-file document anyone can open.
• Bundling receipts and invoices. Photographing a stack of receipts and combining them into one PDF is the simplest possible expense report.
• Sharing a set of photos. A PDF keeps a sequence of images in order, as one attachment, instead of a dozen loose files that arrive scrambled.
• A simple portfolio or moodboard. Designers, photographers and students assemble work samples into a single, page-by-page PDF that looks the same on every device.

Scanning a document with your phone — getting it right

Because the result is an image-only PDF, the quality of your photos is the quality of your document, so a few habits make a big difference:

• Light it evenly. Flat, bright, shadow-free light keeps the text legible. Avoid your own shadow falling across the page and avoid harsh glare.
• Shoot square-on and fill the frame. Hold the camera parallel to the page so the edges stay straight, and get close so the text is large and sharp — more pixels on the page means a crisper PDF.
• Crop to the page before converting, so each PDF page is just the document, not your desk.
• Use Fit and matching orientation. Choose Portrait for a tall page, Landscape for a wide one, and the Fit mode so each image is centred with even margins and never cropped.

And keep the earlier caveat in mind: a phone-scanned PDF is a picture of the text, not the text itself. If you'll need to search or copy from it later, run the finished file through an OCR step to add a real text layer.

Keeping the PDF file size down

A PDF is, roughly, the sum of the images embedded in it, so the size of your download is decided almost entirely by your source pictures — which gives you two levers:

• Format of the source. JPEG photos carry their already-compressed data into the PDF compactly, while PNG and other lossless images are stored uncompressed-by-comparison and balloon the file. For a photo-heavy document, JPEG sources make a much smaller PDF.
• Resolution of the source. A photo far larger than it needs to be wastes bytes. For on-screen reading, modest resolution is fine; even for printing, about 300 DPI is plenty, so a 12-megapixel phone photo of a single sheet of paper is far more detail than the page requires.

If a finished PDF is too large to email or upload, the fix is usually to shrink the images before converting — run them through the Image Compressor or Image Resizer first. Note that the page size you pick (A4 versus Letter versus A3) barely affects the file size at all; it is the image resolution and format that move the needle.