Which File Tool Do I Need? Let the File Decide
There's a small, specific kind of stuck that happens a lot: you have a file, you know something's wrong with it, but you don't know the word for the fix. The photo "won't upload." The PDF is "too big to email." The scan came out "as one long file when it should be three." You open a tools site, and it asks you to pick from a wall of verbs — compress, convert, resize, split, merge — before you've even worked out which one applies.
This guide is the translation layer. It walks through the everyday problems people actually have with PDFs and images, tells you which operation solves each one, and points you at the right tool. And if you'd rather not think about it at all, there's a shortcut at the end.
"It won't upload" or "the file is too big"
This is almost always a size problem, and the fix is compression. For a photo, use an image compressor — it lowers the quality just enough to shrink the file while still looking fine on screen. For a PDF that's heavy because it's full of scans or photos, use a PDF compressor, which re-encodes the pages at a sensible resolution.
One tip before you compress: if an image is also enormous in dimensions (say 6000 pixels wide for a profile picture), resize it first, then compress. Doing both is far more effective than compressing a huge image on its own.
"It's the wrong type of file"
If your iPhone photos arrive as HEIC and a website won't accept them, you need to convert to JPG. If a download came as WebP and a program won't open it, convert it to JPG or PNG. The rule of thumb: JPG for photos, PNG when you need a transparent background or crisp graphics, and WebP when you specifically want the smallest file for a website.
Converting an image to PDF is its own kind of "wrong type" fix — useful when an application portal accepts PDFs but not loose photos, like uploading an ID scan or a receipt.
"It needs to be a specific size"
Passport and visa photos, exam-form uploads and profile pictures all come with exact pixel or file-size requirements. That's a resize (and sometimes a crop) job. Resize changes the dimensions; crop changes what's in frame. For official photos, look for a tool with the preset already built in so you don't have to do the maths.
"The PDF should be in pieces" (or "should be one piece")
If you scanned five documents and they came out as one file, you want to split the PDF — pull out page ranges into separate files. If you have the opposite problem, several PDFs that should be submitted as one, you want to merge them. Both just rearrange whole pages, so nothing loses quality.
If the issue is smaller — a typo, a missing date, a signature, or a number to black out — you don't need to split anything. That's a job for a PDF editor.
"I don't want to upload this anywhere"
Plenty of these files are sensitive: contracts, payslips, ID scans, signed forms. The safest tools do the work in your browser and never send the file to a server. Everything on PixelResize works this way, which is worth checking for whenever a document is personal.
The shortcut: let the file tell you
If you'd rather skip the diagnosis, our Smart Document Assistant does it for you. Drop in a PDF or image and it reads the file locally — type, size, dimensions, transparency, page count, whether a PDF has real text or is a scan — and suggests the right next steps in plain language. Pick one and your file is carried straight into the tool. No jargon, no uploads, no guessing.
Key takeaways
- "Too big to send" → compress (resize first if the dimensions are also huge).
- "Won't open / wrong format" → convert (JPG for photos, PNG for transparency, WebP for the web).
- "Needs an exact size" → resize, and crop to reframe.
- "Should be separate / combined" → split or merge; a small fix to the content is a job for the PDF editor.
- Unsure? The Smart Document Assistant reads the file and recommends the tool — privately, in your browser.