Converting Between JPG, PNG and WebP: Which Tool for Which Job
JPG to PNG, PNG to JPG, or WebP — a practical guide to which conversion you actually need and why the direction matters.
"Convert this to PNG" and "convert this to JPG" sound like the same kind of operation in opposite directions, but what actually happens to the image is very different depending on which way you're converting.
PNG to JPG: real, useful compression
Converting a PNG (especially a photo saved as PNG, which is common and usually unintentional) to JPG applies real lossy compression and typically shrinks the file significantly. This is a genuinely useful conversion when the source doesn't need transparency and file size matters — sharing, emailing, or uploading somewhere with size limits.
JPG to PNG: does NOT undo JPG's quality loss
Converting a JPG to PNG cannot restore detail JPEG compression already removed — PNG will faithfully preserve exactly what's there now, artifacts included, just in a larger file. The only real reason to do this conversion is needing PNG-specific features going forward (like adding transparency in an editor afterward), not to 'fix' or improve a JPG.
WebP: usually smaller than both, at equivalent quality
WebP typically produces smaller files than JPG at the same visual quality, and unlike JPG, it also supports transparency — making it a genuine upgrade over JPG for photos and over PNG for graphics with transparency, when the destination supports it (nearly every modern browser and platform does today).
When NOT to convert at all
If a platform requires a specific format (some upload forms only accept JPG, for example), converting to match that is necessary — but converting a file that's already in the right format for its use case, just because a 'better' format technically exists, adds no real value and just creates an extra file to manage.
One folder, different right answers
A folder is rarely one kind of image. The photos in it usually want JPG or WebP; the screenshots and graphics in the same folder want PNG — converting everything to a single format 'for consistency' makes half the folder worse. Decide per image type, not per folder: photos one way, graphics the other, and the batch stays quick because each conversion is the same few clicks.
What conversion keeps, and what it quietly drops
Conversion re-encodes the pixels into a new container, and some things do not survive the trip. Camera metadata (EXIF — location, camera settings, timestamps) is commonly dropped by re-encoding, which is a privacy plus for sharing but a loss if you were relying on it. Dimensions and crop never change. Transparency survives only into formats that support it — PNG and WebP — and becomes a chosen background colour in JPG.
Convert last: a sensible order of operations
Format is best treated as the export step, done after the editing steps. Crop and resize in whatever format the image is already in, then convert once at the end to the format the destination wants. Converting first and editing after means later tools may re-save in yet another format or quality, and converting twice in a row only multiplies the chances of a lossy step sneaking in.
Quick tips
- If you're not sure a destination supports WebP, PNG and JPG remain the two universally-supported fallbacks.
- Converting doesn't change an image's dimensions or crop — for a wrong-sized image, that's a separate step (Resize or Crop), not something format conversion solves.
- Batch-converting a whole folder makes sense when every image genuinely needs the same target format; convert one at a time when they don't (a mix of photos and flat graphics usually needs different formats, not one-size-fits-all).
- Keep the same filename when converting, so before-and-after pairs stay matched across a folder.
- Converting for a specific upload form? Match exactly the format it asks for — 'better' formats it does not accept are worth nothing.