How to Use Leafzagonal: Resize and Convert Images to WebP
Leafzagonal shrinks heavy PNGs and JPEGs into lean, web-ready WebP files in seconds, entirely on your device. Pick an image, choose a size with the aspect ratio safely locked, dial in quality and download. Nothing is ever uploaded. This guide covers every control and how to choose good settings for photos, screenshots and graphics.
What You Need
- Any modern browser on desktop, tablet or phone. Nothing to install, no account.
- An image in a common format: PNG, JPEG, GIF, AVIF, BMP or WebP.
- Optional: the target width or height you need (for example 1200 px wide for a blog header).
Convert Your First Image
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01
Load an image
Open Leafzagonal and use whichever is easiest:
- Tap the drop zone (“Tap to choose an image or drag and drop”) or press Choose file.
- Drag a file from your desktop onto the drop zone.
- Copy an image (for example a screenshot) and paste it straight into the page with Ctrl/Cmd+V.
The status line shows “Reading image…”, then the file is loaded. It stays on this device the whole time.
Tap the drop zone or Choose file — the image never leaves your device. -
02
Compare Original and WebP output
Two panels sit side by side: Original shows your source with its pixel dimensions, and WebP output shows the converted result. Conversion is automatic: every time you change the size or quality, the WebP preview updates on its own, so you can judge the result before downloading.
Original preview with size, MB, and type before convert; WebP output appears below. -
03
Set the size, ratio locked
In the Size — ratio locked by default section, type a Width (px) or Height (px). While the lock button reads Locked, changing one automatically updates the other, so your image never gets stretched or squashed.
Size (Locked keeps ratio), Scale, WebP quality (~80), rename, then Download — note the KB saved line. The annotated shot above also covers the Scale chips, WebP quality slider, rename field, and Download button used in the next few steps.
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04
Use the quick scale chips or slider
For fast resizing, tap a chip: 25%, 50%, 75% or 100% (original). For anything in between, drag the Scale slider (1–100%). The width and height boxes follow along, and the percentage is shown next to the slider.
Those Scale chips and slider are labeled in the Step 03 controls screenshot above.
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05
Unlock the ratio when you need exact dimensions
Tap Locked to switch it to Unlocked, then enter width and height independently. Do this only when a platform demands an exact box, such as a fixed 1200×630 slot, and you accept some stretching. Otherwise, keep it locked and crop the image first in another editor. Tap again to re-lock; the height snaps back to the original proportions.
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06
Pick a WebP quality
The WebP quality slider runs from 1 to 100 and starts at 80, which the tool itself calls a good balance: lower is smaller, higher keeps more detail. Rough guidance:
- 85–95: screenshots, text, logos and sharp-edged graphics.
- 75–85: everyday photos for websites and blogs (80 is a great default).
- 50–70: thumbnails and previews where the smallest file wins.
Watch the WebP output panel as you drag, and back off if you see blur or blocky artifacts. The quality slider is called out in the Step 03 controls shot.
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07
Name the file
Leafzagonal pre-fills File name (without extension) with your original’s name. Change it if you like (for example hero-1200); .webp is added for you. Rename is marked on the Step 03 controls screenshot.
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08
Download your WebP
Press Download WebP (see the Step 03 controls shot). The status confirms with “Done — …” and the file is saved to your device’s downloads. Then load the next image and repeat. Your size and quality habits will make it fast.
Nothing Leaves Your Device
Leafzagonal is “100% offline — never uploads, no third parties.” It uses only built-in browser features (file reading and canvas) on your device: no uploads, no external scripts, fonts or services. That makes it safe for client work, unreleased designs and personal photos. See the Privacy Policy for details.
Tips
- Resize to the size you actually display. A 4000 px photo shown at 1200 px wastes bandwidth even as WebP.
- For retina/high-DPI screens, export at about 2× the displayed width.
- Keep the ratio locked unless a fixed box is required, because stretched images look wrong instantly.
- Compare file names and sizes: keep an original and a WebP, and serve the WebP on your site.
- Animated GIFs convert using the first frame only, so use them for still images.
- Pair it with Inspectrosite: if your health check flags images without WebP/AVIF versions, Leafzagonal is the quick fix.
Troubleshooting
It says “Could not read image.”
The file may be damaged or in a format your browser can’t decode. Try PNG or JPEG, or re-export it from your editor.
It says “Conversion failed in this browser.”
Very large output sizes can exceed what a browser canvas can handle. Try a smaller size (use the 50% chip), then convert again.
My animated GIF became a still image.
That’s expected: animated images convert using the first frame.
The WebP is bigger than my original.
This happens with images that are already heavily compressed or tiny. Lower the quality a little or reduce the size.
Does it work on my phone?
Yes. It’s mobile friendly: tap the drop zone to pick from your photos, and the download goes to your device.