I Converted 50 Photos into a Single PDF. Four Tools Uploaded Them. One Didn't.
Last month I needed to combine 50 photos of a construction site into one PDF for a property inspection. Years ago I'd reach for Acrobat without thinking. But I don't have Acrobat installed on my current machine and I wasn't about to upload 50 photos of someone's building to a random web server.
So I tested five image-to-PDF converters. The question was simple: which one works fast, keeps files local, and doesn't make a mess of the image order?
What I Tested
50 JPEG photos, average 3MB each, total 150MB. Mix of landscape and portrait orientation. Goal: single PDF, correct page order, reasonable file size, no upload.
| Tool | Uploads files? | Processing time | Output size |
|---|---|---|---|
| formlyapp.org (Image to PDF) | No — browser | ~15 seconds | 142MB (no compression) |
| Smallpdf | Yes — cloud | ~90 seconds (upload + process + download) | 138MB |
| ILovePDF | Yes — cloud | ~110 seconds | 141MB |
| Adobe Online | Yes — cloud | ~80 seconds | 140MB |
| macOS Preview | No — local | ~8 seconds | 145MB |
The Privacy Problem With PDF Converters
Three of the five tools I tested upload your files to a server. If you're combining photos of a construction site, a product design, or anything with personal information — you're sending those images to a company whose privacy policy you probably haven't read.
Smallpdf's privacy policy says they delete files after one hour. That's fine for a one-off, but I've had clients send me PDFs of tax documents, medical records, and legal contracts through these tools without realizing the files hit a server first. The convenience is real, but so is the exposure.
Browser-based tools — like formlyapp.org or macOS Preview — keep files entirely on your device. The PDF is assembled in the browser's JavaScript engine or the OS's native PDF renderer. Nothing leaves your machine. For anything sensitive, this is the only option I'd recommend.
Getting the Page Order Right
Image order is the detail that trips people up. Most tools sort alphabetically by filename. If your photos are named IMG_0001.jpg through IMG_0050.jpg, alphabetical order is correct. But if you renamed some files, or you're mixing photos from two cameras with different naming conventions, alphabetical order puts them in the wrong sequence.
The fix: rename your files before uploading. A simple numbering scheme — 001-photo.jpg, 002-photo.jpg — guarantees correct order regardless of original filenames. On macOS, select all files, right-click, Rename, and choose "Format" with a counter. On Windows, select all, right-click the first file, Rename, type the base name, and Windows auto-appends numbers.
Image Orientation and PDF Margins
Mixing portrait and landscape photos in one PDF is where most converters struggle. The PDF format uses fixed page dimensions per page, so a landscape photo on a portrait page gets letterboxed with white bars. Some tools auto-rotate each page to match the image's orientation, which looks better but can be jarring if you're flipping through a mix of orientations.
If the PDF is for screen viewing, let the converter auto-orient each page. If it's for printing, pick one orientation (usually portrait) and let landscape images get letterboxed — or pre-rotate them before converting.
What I Actually Use Now
For quick jobs where I have fewer than 20 images and they're not sensitive, I still use macOS Preview — it's built in, fast, and the output is fine. For anything sensitive or with more than 20 images, I use formlyapp.org's Image to PDF converter. It handles orientation mixing better than Preview, and everything stays in the browser.
For a 50-photo construction site inspection, the browser tool produced a clean 142MB PDF in about 15 seconds. The files never left my laptop. The building owner got their inspection report. Nobody's server has 50 photos of someone else's property.
Written by Sam Taylor — Full-stack developer. I test tools so I can tell you which ones not to use. More about me →