Most people never choose an image format on purpose. Your phone saves photos one way, a screenshot lands another way, and a designer hands you a third. Then something rejects the file, or it looks blurry, or it weighs ten times more than it should, and suddenly the format matters. This guide walks through the five you actually meet and gives you a simple rule for each.
The short version
- Photographs headed for the web or email: JPG, or WebP if you know the destination supports it.
- Screenshots, logos, icons, anything with sharp edges or text: PNG.
- Anything that needs a transparent background: PNG or WebP, never JPG.
- iPhone photos you need to share with non-Apple devices: convert HEIC to JPG first.
- The smallest possible file with good quality: AVIF or WebP, with a JPG fallback for older software.
JPG: the default for photographs
JPG (also written JPEG) has been the standard way to store photos for three decades, and it earns that position. It uses lossy compression tuned for continuous-tone imagery, which means it throws away detail your eye barely notices in order to make the file dramatically smaller. A photo that would be several megabytes as a raw capture usually lands between a few hundred kilobytes and a couple of megabytes as a JPG at good quality.
The trade-offs are worth knowing. JPG has no transparency, so any transparent area becomes solid white. It also compresses in 8-pixel blocks, so hard edges and small text can pick up faint halos, which is why screenshots look worse as JPG than photos do. And every time you re-save a JPG it loses a little more, so it is a format for finished images, not for files you plan to keep editing. When a photo is too heavy, you rarely need to change format at all, you just compress the JPG a little harder.
PNG: sharp edges and transparency
PNG is lossless, meaning it stores every pixel exactly. That is the opposite priority from JPG, and it makes PNG the right home for anything where crisp edges matter: screenshots, user-interface mockups, logos, line art, diagrams, and any graphic with flat areas of solid color. It also supports a full alpha channel, so a logo can sit on any background without a white box around it.
The cost is size. A full-screen PNG screenshot can easily be several megabytes, because it never discards anything. For a photograph, PNG is usually the wrong choice, the file will be far larger than a JPG for no visible benefit. If you have a PNG that is only heavy because it is a photo, convert it to JPG. If you need a lossless copy of a JPG to edit, you can go the other way with JPG to PNG, though remember that this cannot recover detail the JPG already lost.
WebP: modern, small, and flexible
WebP is Google's format, and it does something neat: it supports both lossy and lossless compression, plus transparency, in a single format. For photos it typically comes out 25 to 35 percent smaller than a JPG of similar quality, and for graphics it can keep transparency like a PNG while staying much smaller. Every current browser displays WebP, which is why so many websites now serve it.
The catch is outside the browser. Some older desktop apps, a few social platforms, and certain upload forms still do not accept WebP, and you end up with a .webp file you cannot open. When that happens, convert WebP to JPG or WebP to PNG depending on whether you need transparency. Going toward WebP to save space is just as easy with PNG to WebP or JPG to WebP.
HEIC: the iPhone format
If you own a recent iPhone, your camera probably saves photos as HEIC by default. It is an efficient, modern format that stores a high-quality photo in about half the space of a JPG. The problem is purely one of compatibility: Windows, Android, and a lot of websites and email clients still cannot open HEIC directly, so a photo that looks fine on your phone arrives as an unopenable file for the person you sent it to.
The fix is to convert HEIC to JPG before you share. JPG is understood by everything, everywhere, so it is the safe lingua franca for sending photos to someone whose device you do not control. You lose the space savings, but you gain the certainty that the image will actually open.
AVIF: the newest and smallest
AVIF is the most recent arrival, built on the AV1 video codec. It usually produces the smallest file of all at a given quality, often around half the size of a comparable JPG, and it supports transparency and a wider range of colors. Browser support is now broad, so it is a strong choice for a website that wants fast-loading images.
Support in older software and some apps still lags, though, so an AVIF file can be awkward to hand to someone directly. When you receive one and something refuses to open it, convert AVIF to JPG for maximum compatibility. Think of AVIF and WebP as the space-savers you use when you control the destination, and JPG as the universal format you reach for when you do not.
A rule you can remember
If it is a photo and it is leaving your hands, use JPG. If it has text, sharp lines, or a transparent background, use PNG. If you control the website or app it is going to and want it smaller, use WebP or AVIF. And if a file simply will not open, convert it to JPG, which every device on earth understands. Every conversion mentioned here happens right in your browser on this site, so none of your images are ever uploaded anywhere.