Image to PDF

PDF began as an Adobe format and is now published by ISO, as the timeline above shows, which is why every computer, phone and browser can open one without extra software. That makes it the safest way to hand over a set of pictures as one document: the pages stay in order, nothing gets resized by an email client, and the person on the other side sees exactly what you sent.

The first decision is the page size. Same as image makes every page exactly the size of its picture, which suits a portfolio or a photo album meant for screens: no white space and no cropping, and each page can have a different shape. Choose a paper size when the PDF will be printed or when a form expects a normal document. A4 is 210 × 297 mm under ISO 216 and is used across most of the world; Letter (8.5 × 11 inches) and Legal are the North American sizes. A3, A5 and a custom width and height in millimeters cover posters, booklets and anything else.

Orientation is set to Auto, which turns each page to match its picture: landscape photos get landscape pages and portrait photos get portrait pages, even in the same PDF. Force portrait or landscape if every page must face the same way, for example when the PDF will be bound or printed double-sided.

When the image and the page have different shapes, Image on page decides what happens. Fit shows the whole picture and leaves white space at the sides or top and bottom. Fill page covers the page edge to edge and crops what overflows. Actual size places the image at the print size its DPI implies, which is what you want for a scan that should print at its original scale. Margin adds white space around each image: small is 5 mm, medium 10 mm and large 20 mm. Margins are ignored when the page is the same size as the image, since there is no page around the picture to hold them.

Images per page places two or four pictures on each page in a grid instead of one. Two per page is the usual layout for the front and back of an ID card, a driving license or a two-sided receipt, so both sides travel as a single sheet. Four per page makes a contact sheet: a quick overview of a set of photos that someone can print on one sheet and mark up. With several images on a page, choose a paper size rather than Same as image, so the grid has a fixed page to fill.

Page order is where image-to-PDF jobs most often go wrong, because files picked from a folder or a phone gallery do not always arrive in the order you see on screen. The file list on this page is the order of the pages. Drag a file up or down to move its page, and remove any picture that slipped in by mistake.

Two automatic orders help with longer jobs. File name sorts alphabetically, which suits scanners that save pages as scan001, scan002 and so on. Date taken reads the capture time stored by the camera, so photos of a multi-page document shot on a phone line up in the order you took them, even if they were renamed. Pictures without a capture date, such as screenshots and downloaded images, have nothing to sort by, so check those by eye.

It helps to decide on the order before you start adding files. For paperwork, the usual sequence is the form itself first, then supporting documents in the order the form lists them. For a set of receipts or invoices, chronological order makes the PDF easier to check. If you will add more pages later, give the files numbered names now, so a second batch slots in where it belongs.

Output decides whether you get one document or many. One PDF gives a single file with a page per image. One PDF per image gives a separate file for every picture, downloaded together in a ZIP, which is what some application systems want when each document goes into its own upload field. If you already have PDFs and only need to join them, the Merge PDF tool is the better tool.

A PDF of photos is mostly the photos themselves, so its size grows with every page. A handful of full-resolution phone pictures can easily pass the limit of an upload form or an email attachment. PDF file size handles this in one step: set it to Target size, type the limit in KB or MB, and the images inside are recompressed, and reduced in pixel size if needed, until the complete PDF is at or just under the number.

Most of the weight comes from the pixel count, not from the number of pages. A phone photo of a sheet of paper holds far more pixels than a readable page needs, so the target-size search usually reduces the pixel size of such pages first and leaves their text perfectly legible. Photos meant to be looked at closely, such as a portfolio, suffer more from a tight limit, and for those it is worth asking whether the recipient really needs everything in one file.

With Best quality, the images keep their pixel size and are stored as JPEG at the Image quality you set, 85 by default, which keeps photos sharp. Lower values make the file lighter at the cost of fine detail; text on a scanned page usually stays readable well below the default. If the PDF already exists and is too large, the Compress PDF tool works on the finished file instead.

Metadata matters in a PDF, too. Strip metadata removes GPS position and camera details from every image inside and leaves the PDF's own properties empty, so the document does not reveal where the photos were taken or which phone took them. It is on by default; switch it off only when the camera data is the point, for example in a photo report for an insurance claim.

PDF/A (archive) creates a PDF/A-2b file, the archiving profile of PDF that embeds everything needed to display the document in the future. Turn it on only when the receiving system asks for PDF/A, as some courts and government portals do; for everything else a regular PDF is smaller and opens the same way. The limits that most often matter when you send the result: