Five image formats cover almost everything you will meet today: JPG, PNG, WebP, HEIC and AVIF. They can all hold the same photo, but they make different trade-offs between file size, quality, transparency and, most importantly, who can open the file. Most “my image won’t upload” problems come down to picking the right one for where the picture is going.
This guide gives you the short answer first, then explains each format, where it fails, and how to switch between them without losing more quality than you need to.
The short answer
- Uploading to a form, portal or app? Use JPG. It is the one format every system accepts. If the form also names a size limit in KB, see Compress Image to 20KB.
- Logo, icon, screenshot or anything with a transparent background? Use PNG.
- Images for your own website? Use WebP (or AVIF with a fallback), because they load faster than JPG and PNG.
- Photos on an iPhone? They are probably HEIC already. Keep the originals, and convert a copy to JPG when you need to share or upload it.
- Saved a picture from a website and it ends in .avif or .webp? Convert it to JPG before you try to use it elsewhere.
The five formats side by side
| JPG (JPEG) | PNG | WebP | HEIC | AVIF | |
|---|---|---|---|---|---|
| Compression | Lossy | Lossless | Lossy or lossless | Lossy | Lossy or lossless |
| Transparent background | No | Yes | Yes | Yes | Yes |
| Animation | No | Only as APNG | Yes | Not in practice | Yes |
| Colour depth | 8-bit | Up to 16-bit | 8-bit | Depends on the camera | 8, 10 or 12-bit, HDR |
| Opens in web browsers | All | All | All current browsers | Safari 17 and later only | Chrome 85+, Edge 121+, Firefox 93+, Safari 16.4+ |
| Accepted by upload forms | Almost always | Usually | Sometimes | Rarely | Rarely |
| Best for | Photos you share or upload | Graphics, text, transparency | Images on websites | Storing phone photos | Images on websites |
| Largest image | 65,535 × 65,535 px | Effectively unlimited | 16,383 × 16,383 px | Device-dependent | Effectively unlimited |
Lossy means the file throws away detail you are unlikely to notice in exchange for a much smaller size. Lossless means every pixel is kept exactly. Neither is “better”: lossy is right for photos, lossless is right for sharp edges and text.
JPG: the format that works everywhere
JPG (also written JPEG) has been the standard photo format since the 1990s, and that history is its biggest strength. Every phone, computer, printer, email client, government portal and job application site can read it.
Where it is strong: photographs, especially when the file has to go somewhere you do not control. A typical phone photo saved as JPG at 80% quality looks the same as the original to most people at a fraction of the size.
Where it fails:
- No transparency. Save a logo with a see-through background as JPG and the background turns solid, usually white or black.
- Text and sharp lines get smudged. JPG compresses in small blocks, so around crisp edges you see faint “ringing” or blotches. Screenshots of documents look noticeably worse than in PNG.
- Every re-save loses a bit more. Open a JPG, edit it, save it as JPG again, and repeat: each round adds artefacts. Keep an original and export from that.
If you need a JPG from something else, use PNG to JPG, WebP to JPG, HEIC to JPG or AVIF to JPG.
PNG: exact pixels and transparent backgrounds
PNG stores every pixel exactly, and it supports full transparency, including soft, semi-transparent edges such as a drop shadow.
Where it is strong: logos, icons, diagrams, screenshots, scanned signatures on a transparent background, and any image you plan to edit further, because saving it again does not lose quality.
Where it fails:
- Photos become huge. Because nothing is thrown away, a photo saved as PNG is often several times larger than the same photo as JPG, with no visible benefit. This is the most common reason a form says “file too large”.
- Some forms only say “JPG/JPEG”. Plenty of application portals reject PNG even when the picture is fine.
If you have a PNG photo that is too big, PNG to JPG usually shrinks it dramatically. Going the other way, JPG to PNG gives you a lossless copy for editing, but it cannot bring back detail the JPG already discarded. To turn a vector logo into a PNG, use SVG to PNG.
WebP: smaller files for the web
WebP was designed by Google as a single web format that could replace both JPG and PNG. It has a lossy mode for photos and a lossless mode for graphics, and both modes support transparency and animation. According to Mozilla’s developer documentation, lossy WebP is typically 25–35% smaller than a JPG of similar visual quality, and lossless WebP about 26% smaller than PNG.
Where it is strong: images on your own website or blog. Every current browser shows WebP, and smaller images mean faster pages, which matters for visitors on mobile data.
Where it fails:
- Outside the browser, support is patchy. Older photo editors, some printers, many upload forms and some messaging apps still refuse .webp files. That is why pictures saved from websites often “won’t open” or “won’t upload”.
- Size limit. A WebP image cannot be larger than 16,383 pixels on either side, so very large panoramas and print scans need another format.
- Older Apple devices. On a Mac, Safari only shows WebP from Safari 14 on macOS Big Sur (11) or later.
To create WebP files for your site, use Image to WebP. To use a WebP you downloaded, convert it with WebP to JPG for photos or WebP to PNG if it has a transparent background.
HEIC: what your iPhone saves by default
HEIC is Apple’s name for photos stored in the HEIF container. Apple’s support documentation says iPhone 7 and later (on iOS 11 or later) can capture photos this way; when the camera’s format setting is “High Efficiency”, that is what you get. The files are much smaller than JPG at the same quality, which is why Apple chose it.
Where it is strong: storing photos on an Apple device, where everything opens it seamlessly.
Where it fails:
- Almost nothing outside Apple shows it. At the time of writing, Can I Use lists Safari 17 and later as the only browsers that can display HEIC. Chrome, Edge and Firefox cannot, and the same applies to most upload forms and many Windows and Android apps. Can I Use notes that HEIC is complex and expensive to license, which is a large part of why.
- Sharing sometimes converts it, sometimes does not. Apple says photos sent by AirDrop, Messages or email may be converted to JPG automatically, but copying files in other ways (cloud drives, some cables, web uploads) can hand over the original .heic file.
Two fixes:
- Convert the photos you need to share with HEIC to JPG. It runs in your browser, so the photos are never uploaded.
- If you would rather your iPhone shot JPG from now on, Apple’s instructions are: open Settings, tap Camera, then Formats, and choose Most Compatible. This only affects new photos, and they will take more storage space.
AVIF: the newest, most efficient format
AVIF is built on the AV1 video codec. Like WebP it supports lossy and lossless compression, transparency and animation, and it also supports HDR and 10- or 12-bit colour, so it can show smoother gradients and brighter highlights than JPG. Many image CDNs now serve AVIF automatically, which is why you increasingly find .avif files when you save a picture from a website.
Where it is strong: photos on websites, where it usually produces the smallest file of all five formats for a given visual quality.
Where it fails:
- Only recent browsers. Can I Use lists full support from Chrome 85, Edge 121, Firefox 93 and Safari 16.4 (iOS 16 on iPhone and iPad). Older browsers, older Windows photo viewers and almost every upload form will not take it.
- No progressive loading. A JPG can appear blurry-then-sharp while it downloads; an AVIF appears only once it has fully arrived.
- Slower to create. Encoding AVIF takes noticeably more processing time than JPG or WebP, which matters if you convert large batches on a phone.
If you have an AVIF you need to use somewhere else, AVIF to JPG converts it in your browser and warns you up front if your browser cannot read AVIF.
Which format for which job
| You want to… | Use | Why |
|---|---|---|
| Upload a photo to a job, university or government form | JPG | Accepted everywhere; easy to bring under a KB limit |
| Upload a signature to a form | JPG, unless the form asks for PNG | Most forms specify JPG; see Signature Resizer |
| Send photos on WhatsApp or by email | JPG | Opens on every phone and computer |
| Put a logo on a website or in slides | PNG (or SVG if the site accepts it) | Keeps a transparent background and sharp edges |
| Share a screenshot of text or a chart | PNG | No smudging around letters |
| Speed up images on your own website | WebP, or AVIF with a WebP/JPG fallback | Smallest files that browsers display |
| Keep the best copy of your phone photos | HEIC on iPhone, or the camera’s default | Smallest size at full quality; convert copies when sharing |
| Print a photo at a shop | JPG at high quality | What print kiosks and labs expect |
Converting without making things worse
A few rules keep quality loss to a minimum:
- Convert from the original, not from a copy of a copy. Each lossy save (JPG, lossy WebP, AVIF, HEIC) throws away a little more.
- Converting lossy to lossless does not restore anything. Turning a JPG into a PNG makes a bigger file that looks exactly like the JPG.
- Transparency is lost when you go to JPG. Converting a PNG, WebP or AVIF with a transparent background to JPG fills the background with a solid colour. Choose PNG instead if the transparency matters.
- Dimensions matter more than format for file size. A 4,000-pixel-wide photo will be large in any format. If a site only shows it 1,200 pixels wide, Resize Image first, then pick the format.
- Hitting a KB limit is a separate step. Change the format first, then use Compress Image or, for an exact limit such as “under 50 KB”, Compress Image to 20KB, which lets you type any target.
Every ToolsYes converter runs inside your browser, so nothing is uploaded. That makes them safe for ID photos, signatures and personal documents, and it is also why the browser itself has to understand the format you start from. If you need to put several images into one document instead, JPG to PDF combines them into a single PDF.
Sources
Format features, size limits and browser support were checked on 9 November 2026 against:
- Mozilla, Image file type and format guide (MDN Web Docs): compression, transparency, colour depth, maximum dimensions and WebP size comparisons.
- Can I Use, AVIF image format and HEIF/HEIC image format: browser versions.
- Apple Support, Using HEIF or HEVC media on Apple devices: which iPhones capture HEIC, automatic conversion when sharing, and the Most Compatible setting.