How to convert images to PDF, and why the settings matter
Turning a pile of photos into a single PDF is one of those tasks that sounds trivial until you actually need it: a landlord wants the receipts in one file, a university wants a scanned form as a document rather than five separate pictures, a client wants the design mockups in something they can flip through. This page does that conversion locally, and the short guide below explains the choices it puts in front of you so the result comes out the way you expect.
Why put images in a PDF at all?
A PDF fixes three problems that loose image files have. It keeps a defined order, so page two always follows page one instead of depending on how someone's file manager sorts names. It travels as a single attachment, which matters when an upload form accepts one file or an email starts bouncing at ten attachments. And it carries a fixed page geometry, so what you see is what prints — an image on its own has no notion of paper size, and every printer will guess differently.
What happens to JPG, PNG and WebP
Every image you add is decoded by the browser and re-encoded as JPEG before it goes into the document, at the quality you pick with the slider. That is what lets the tool accept formats a PDF cannot hold natively — WebP and AVIF among them — and it is also why a PNG with a transparent background comes out on white: PDF pages are opaque, and transparency has to resolve to something. If you need the transparency preserved, a PDF is the wrong container; keep the PNG.
A4, Letter, or fit to the image?
Pick A4 if the document will be printed or submitted anywhere outside the United States, and Letter if it will be printed in the US or Canada. In both cases each image is scaled to fit inside the page and centred, and the orientation follows the image: a wide photo produces a landscape page, a tall one a portrait page, so nothing is ever rotated or cropped against your will.
Choose Fit when the PDF is meant to be read on a screen rather than printed. Each page then takes the exact proportions of its image, so there are no white bands at the sides. It is the right option for comic pages, screenshots, portfolios and product sheets.
Quality, margins and file size
The quality slider is the single biggest lever on the final size. At 90% a phone photo lands around a few hundred kilobytes per page; at 100% it can triple with no visible gain, and below 70% the compression starts showing on skin tones and flat backgrounds. If you are assembling twenty scanned receipts and the total needs to clear an upload limit, drop to 75–80% before you consider anything else.
Margins matter for printed documents: without one, printers that cannot do borderless output will clip the edges of your image. The 1 cm default is a safe compromise. Set it to none only when the PDF stays digital.
Why this runs in your browser
The documents people most often turn into PDFs are exactly the ones they should be careful with: identity documents, medical results, invoices, contracts, bank statements. On a conventional online converter every one of those files is uploaded to a machine you do not control. Here the PDF is assembled by JavaScript running on your own device, and nothing is transmitted — you can disconnect from the internet after the page loads and it still works.