Which image format should you choose?
What does an image converter do?
An image converter re-encodes your file from one format to another. The pixels you see stay the same; what changes is how the file stores them. That change decides three things: how large the file is, whether it can carry transparency, and which programs and devices can open it.
ImageConvert reads JPG, PNG, WebP, GIF, HEIC and AVIF files and writes JPG, PNG, WebP or AVIF. The framing and dimensions are never touched; only the container changes.
JPG: the universal photo format
JPG is the oldest and most widely supported format for photos. It compresses with a small, usually invisible loss and produces small files, which is why cameras, phones and every website accept it.
Its two limits matter: it cannot store transparency, and saving it over and over slowly wears the quality down. Use JPG for photos you share, upload to forms or attach to email.
PNG: lossless, with transparency
PNG keeps every pixel exactly as it is and supports a full transparency channel. That makes it the right choice for logos, icons, interface screenshots and anything with sharp text or flat color areas.
The trade-off is size: a photo stored as PNG can be five to ten times larger than the same photo as JPG. If the image is a photo and transparency does not matter, PNG is usually wasted space.
WebP and AVIF: the modern pair
WebP does both jobs: it compresses photos like JPG and keeps transparency like PNG, usually in a smaller file than either. Every modern browser displays it, which makes it the practical default for websites.
AVIF is the newest option and squeezes files even smaller at the same visible quality. Support is broad on current devices but thinner in older programs, so AVIF is best when you control where the image will be shown.
HEIC: the iPhone format
iPhones save photos as HEIC to save space. The catch is compatibility: many Windows programs, websites and older devices cannot open it. If someone sent you a .heic file that refuses to open, converting it to JPG solves it in one step.
Photos taken with a phone also carry the capture orientation inside the file. ImageConvert applies that orientation automatically, so converted photos never come out sideways.
Transparency: what happens when formats change
JPG has no transparency channel. Take a transparent PNG into JPG and the see-through regions must be filled with a solid color; ImageConvert lets you pick that color and defaults to white.
If you need to keep the transparency, choose PNG, WebP or AVIF as the output. Going from JPG to PNG does not create transparency either: the JPG had none to begin with, so the PNG comes out fully opaque.
Quality setting: what the number means
For JPG, WebP and AVIF the quality slider trades detail for size. The default 85 is where photos lose nothing the eye can catch while the file shrinks clearly. Below 60, flat color areas start to show blocky artifacts.
PNG ignores this setting because it is lossless: it always stores every pixel exactly, no matter what the slider says.
Converting a whole folder at once
A single request accepts up to 20 images and converts each one with the same settings. The results come down separately, or as one ZIP archive that keeps the original names with the new extension.
Bulk conversion is the practical route when a client sends a folder of HEIC photos, or when you are moving a site's assets to WebP in one pass.