Images & Photos
JPG, PNG, WebP or HEIC - which format when?
Picking the right image format is the single biggest lever for file size - often bigger than any quality slider. This is the decision guide we wish every upload form linked to.
Key takeaways
- Photos: JPG is the universal choice; WebP is 25-35% smaller at the same quality but not accepted by every portal.
- Screenshots, logos, anything with text or transparency: PNG - JPG makes text edges smudgy.
- HEIC from iPhones is efficient but widely rejected by upload forms - convert to JPG before submitting.
- Animations: short clips beat GIF as MP4 or animated WebP at a fraction of the size.
The formats in one table
| Format | Best for | Transparency | Upload compatibility |
|---|---|---|---|
| JPG | photos, scans | no | accepted everywhere |
| PNG | screenshots, logos, text, transparency | yes | accepted everywhere |
| WebP | web images - photos and graphics | yes | most modern sites, some portals reject it |
| HEIC | iPhone camera storage | yes | frequently rejected outside Apple |
| AVIF | smallest photos, modern browsers | yes | growing, still patchy |
| GIF | legacy animations | 1-bit | everywhere, but huge files |
| SVG | icons, diagrams, vector art | yes | great on the web, rarely accepted by forms |
Photos: JPG by default, WebP when accepted
JPG compresses photographs with an adjustable loss that human eyes tolerate remarkably well. Quality 80 is visually near-transparent for most photos and dramatically smaller than quality 100. Every form, portal and CMS on the planet accepts JPG - which is why it remains the safe default.
WebP produces files roughly 25-35% smaller than JPG at comparable quality and supports transparency. Browsers have supported it for years; older upload portals sometimes have not caught up. Practical rule: use WebP for your own website, JPG for anything you submit to third parties.
Graphics: PNG, and why JPG ruins screenshots
JPG's compression is tuned for smooth gradients, not hard edges. Compress a screenshot or a logo as JPG and the sharp edges of letters grow blurry halos. PNG compresses losslessly, keeps edges crisp and supports full transparency - at a larger file size for photographic content.
Rule of thumb: if it came out of a camera, JPG or WebP. If it came off a screen or a design tool, PNG. If it needs a transparent background, PNG or WebP - never JPG, which fills transparency with white.
HEIC: great on iPhone, rejected elsewhere
iPhones store photos as HEIC by default - technically excellent, roughly half the size of an equivalent JPG. The problem starts when a government portal, job board or web form silently rejects the format or, worse, accepts the upload and then fails processing it.
Before submitting anywhere important, convert HEIC to JPG. The FileSizeFix image tools accept HEIC directly and convert it in the browser, so this takes one step - pick the file, choose JPG output, set your KB target if the form has one.
Animations: stop exporting GIF
GIF is limited to 256 colors and compresses each frame poorly - a few seconds easily weigh 10-20 MB. The same clip as MP4 is typically 90% smaller, and animated WebP sits in between with broad browser support. Keep GIF only where a platform strictly requires it.
Frequently asked questions
Which image format has the smallest file size?
For photos at comparable quality: AVIF is smallest, then WebP, then JPG. For graphics with few colors, PNG can beat them all. The right format for the content matters more than any quality setting.
Should I upload WebP to application portals?
Only if the portal explicitly accepts it. Many portals validate file extensions strictly and expect JPG, PNG or PDF - when in doubt, JPG is the safe choice.
How do I convert HEIC to JPG without installing anything?
Open the FileSizeFix image compressor in your browser, select the HEIC file and choose JPG as the output format. Conversion runs locally on your device - the photo is not uploaded.
Does converting JPG to PNG improve quality?
No. PNG cannot restore detail that JPG compression already discarded - it just stores the existing pixels losslessly in a larger file. Convert in that direction only when a form requires PNG.