The two usual reasons When a website refuses a photo from your iPhone, it is almost always one of two things. First, the file type: iPhones save photos as HEIC by default, and many forms only accept JPG or PNG. Second, the file size: an iPhone photo is often 2–5 MB, while forms commonly limit uploads to 200 KB, 100 KB or even 50 KB. Some forms reject a file for both reasons without saying which.
Fix both at once Drop the photo into the box at the top of this page. FitKB decodes the HEIC file in your browser, converts it to a standard JPEG, and compresses it to the limit you choose. The default here is 200 KB; change it to whatever the form says. The result shows the exact size in KB and bytes, the pixel dimensions, and a side-by-side preview.
On the iPhone itself In Safari, tap the box, then choose Photo Library or Browse. Pick the photo, press Convert, and tap Download JPG. The file is saved to your Downloads (Files app), and from there you can attach it to the form.
Stop it happening again On your iPhone, open Settings → Camera → Formats and choose "Most Compatible". New photos will be saved as JPG. This does not shrink file size, so you may still need to compress for strict forms.
Still rejected? Check the form's rules for pixel dimensions, aspect ratio, or a minimum size. Use range mode for "between X and Y KB" requirements.
Privacy, in plain terms: FitKB runs entirely in your browser tab. Your photo is decoded and re-encoded on your own device using the browser canvas. Nothing is uploaded, there are no analytics or tracking scripts, and the page's Content-Security-Policy blocks connections to other servers. You can switch off Wi-Fi after the page loads and it keeps working.