Two small technical details cause a surprising number of failed uploads. The first is format: a portal says "JPG/JPEG only" and your phone saved the photo as HEIC, or a screenshot came out as PNG, or a downloaded image is WebP. The second is DPI: the notification says "200 DPI" and there is no obvious way to see or change what your file says. This page handles both, for one image or a whole batch, in your browser.
It is deliberately simple: pick a format, optionally a DPI, and download. If you also need exact pixels or a KB limit, use the photo & signature resizer instead — it converts formats too, as part of producing a portal-ready file.
| Format | Best for | Transparency | DPI stored | Notes |
|---|
| JPG / JPEG | Photos and scans; almost every exam upload | No | Yes (JFIF header) | Lossy: smaller files, adjustable quality |
| PNG | Screenshots, logos, graphics with sharp edges | Yes | Yes (pHYs chunk) | Lossless: large files for photos |
| WebP | Websites; small files at good quality | Yes | No standard field | Rarely accepted by government portals |
For application forms, the answer is nearly always JPG: all 84 presets in our data specify JPEG. Choose PNG only when a form explicitly asks for it or when you need transparency. WebP is great for websites, but not for forms.
One common mistake is renaming a file — changing "photo.png" to "photo.jpg" — instead of converting it. The name changes, the contents don't, and portals that check the actual file type reject it. Converting re-encodes the image in the new format.
How do I convert iPhone HEIC photos to JPG?
iPhones save photos as HEIC by default because it produces smaller files, but many websites and older computers cannot open HEIC. Add the HEIC files here and choose JPG. On Safari the browser decodes HEIC itself; in other browsers the page loads a HEIC decoder (heic2any) that is hosted on this site, the first time it is needed. Either way the conversion happens on your device. If you would rather stop the iPhone making HEIC files, go to Settings → Camera → Formats and choose "Most Compatible" — new photos will then be JPEG.
After converting, open the JPG once before uploading and check that it is upright and complete. If a photo comes out sideways, rotate it in the main editor, which has rotate buttons and saves an upright JPG at the size your form needs. Keep the original HEIC too: it is the highest-quality copy you have, and it is the best starting point if you need a different size or format later.
What does changing the DPI actually do?
DPI (dots per inch) is a number stored in the file header that says how large the image should be when printed. It does not change the pixels. A 600 × 600 px image marked 300 DPI prints at 2 × 2 inches; the same pixels marked 200 DPI print at 3 × 3 inches. On screen, both look identical.
So when a form says "200 DPI", there are two possible meanings. Usually it is shorthand for a physical size at a resolution — for example "3.5 × 4.5 cm at 200 DPI", which means 276 × 354 pixels. In that case what matters is the pixel count, and you should resize with resize in cm or the main editor. Sometimes an upload system also reads the DPI field itself, and rejects files that say 72 or 96. Setting the DPI here fixes that second case without touching the pixels. Doing both — the right pixels and the right DPI value — covers every interpretation.
Changing the DPI value alone never makes an image sharper. If a portal says your photo is "low resolution", the fix is more pixels from the original photo, not a bigger number in the header.
How do I change a photo to 200 or 300 DPI?
- Add the photo and choose JPG (or PNG) as the output format.
- Type 200 or 300 in "DPI to embed".
- Download. The result shows "DPI in file: 200" (or 300); the original's DPI is shown too, or "no DPI stored" if it had none.
For JPG the tool writes the DPI into the JFIF header; for PNG it writes a pHYs chunk. Windows (Properties → Details), macOS Preview (Tools → Show Inspector) and most image editors display the new value. WebP has no standard DPI field, so choose JPG or PNG when DPI matters.
Which forms mention a DPI?
In our data, DPI appears mostly alongside sizes given in centimetres or millimetres. These are the documents with a physical size, the DPI and the resulting pixel size, generated from the same data file as the editor's presets:
Documents in data/presets.json specified in cm/mm. Verify with the official notification.
The main editor sets the DPI automatically when you choose one of these presets, so if you use it you don't need a separate conversion step.
Why won't a portal accept my JPG?
If you converted to JPG and the upload still fails, the format is usually no longer the problem. Work through these in order:
- File size. Converting does not target a size, and a high-quality JPG from a large photo can be several megabytes. Use compress to a KB target or the main editor.
- Pixel dimensions. Many portals check the width and height exactly. Resize with the editor or resize in cm.
- Extension case or spelling. Some older systems accept ".jpg" but not ".jpeg" or ".JPG". Files from this tool end in lower-case ".jpg"; renaming the extension between .jpg and .jpeg is harmless because both are the same format.
- File name. Spaces, brackets or very long names occasionally cause trouble. A short name such as "photo.jpg" is safest.
- CMYK or unusual colour modes. Scans saved by some office software use CMYK, which a few browsers and portals handle badly. Re-converting here always produces a standard RGB JPG.
- Progressive JPEGs. Rarely, an old portal chokes on progressive encoding; browsers write baseline JPEGs, so a file converted here avoids that too.
If none of these apply, read the error message word for word — it usually names the rule that failed.
What quality setting should I choose?
For JPG, 85–92 % is visually indistinguishable from the original for most photos and much smaller than 100 %. Go higher for scans with fine text; go lower only when you need a smaller file and can't reduce the pixel size. If you are aiming at a specific file size, don't guess the quality here — use compress to a KB target, which searches for the best quality that fits. Converting a JPEG to JPEG again at a lower quality loses a little detail each time, so start from the original whenever you can.
What happens to transparent backgrounds?
PNG and WebP can have transparent areas; JPG cannot. When you convert a transparent image to JPG, the transparent parts are filled with the background colour you choose — white by default, which is what most forms want for signatures and cut-out photos. Converting to PNG or WebP keeps the transparency as it is.
Can I convert many images at once?
Yes. Add several files and they are converted with the same settings; each one gets its own download button, and "Download all" saves them one after another (your browser may ask once for permission to download multiple files). Everything happens locally, so there is no upload waiting time and no limit on file count other than your device's memory.
The converter works offline once loaded, never uploads your images, and adds no watermark. Format and DPI requirements vary between portals and are revised between notifications — verify with the official notification before you upload.