ConvertHow to Convert PNG to WebP and Keep Transparency
To convert a PNG to WebP, choose WebP in the image converter and compare the saved result with the original. The comparison matters more than the extension. A smaller file helps when it still looks right on the page or in the app where it will be used. If the image has a transparent background, test the edges against the actual background color before replacing the PNG.
When is WebP a useful choice?
WebP is useful for images delivered on the web when the destination accepts it. A screenshot in a help center, a product card with a transparent cutout and a blog image are three reasonable candidates. The best settings differ. Text in a screenshot can show artifacts that are easy to miss in a photo. A cutout may need particular care where wisps of hair or thin outlines meet a colored background.
Check the place you intend to upload the file first. Some publishing workflows require a PNG even if a browser can display WebP. If the destination lists PNG and JPG only, keep a copy in an accepted format. You can still use WebP for a separate website copy and name it clearly so nobody sends the wrong file.
Separate dimensions from encoding quality
The number of pixels and the way those pixels are encoded both affect file size. A PNG that is 3600 pixels wide may contain detail far beyond what a small sidebar uses. Scaling it to the width needed by that sidebar can be more effective than pushing the quality slider lower while keeping the original dimensions.
Measure what the destination needs. If a product card occupies about 400 CSS pixels and you want to provide enough detail for a display that uses two device pixels per CSS pixel, an 800 pixel source is a reasonable example to compare. A full screen image may need more. Treat that calculation as a starting point and inspect the actual page layout rather than applying one width to every image.
Convert the PNG in your browser
Open Convertly and choose Image Converter. Add the PNG, then select WebP in the format menu beside the file. Open Advanced settings if you need to change the quality or cap the width. A maximum width below the source width scales the height proportionally. With the width unset, the converter uses the original dimensions.
Convert and download the result. Check the file extension and open the saved copy in the application that will use it. Some browsers may be unable to encode the selected output format. If the converter reports that limitation, use a browser with WebP encoding support or choose an accepted alternative format for the destination. Preserve the source PNG so you can make another version later.
How to compare two exports
Try one export at the default quality and another at a lower setting. Use the same dimensions in both so you are comparing encoding quality rather than two changes at once. Look at the file sizes and inspect the images side by side at the size readers will actually see. Zoom in on the details you care about after you make that first comparison.
For a screenshot, look at small type, thin rules and high contrast corners. For a photo, examine smooth sky or skin tones and sections with a lot of texture. For a transparent icon, inspect the boundary where the icon meets the background. If the smaller file makes an important label difficult to read, a modest size reduction may be the better tradeoff.
Does WebP keep the transparent background?
WebP supports transparency and Convertly draws WebP output without filling the canvas with white. Transparent areas in a normal source PNG can therefore remain transparent when the browser encodes the result. An opaque area already present in the source remains part of the image. A picture of a white wall behind a product, for instance, still contains that wall after conversion.
Use a simple background test before publishing. Place the exported asset on a dark slide and then on a light slide. A box where you expected a cutout usually means the source already had a background. Look for unintended fringes too. If the image is for a dark navigation bar, judge the final export on that exact color.
Why is the WebP bigger?
Some PNGs are already very compact. A small flat icon or a tightly optimized screenshot may leave little room for improvement. The WebP encoder may choose a representation that takes more bytes at the setting you selected. The appropriate result is the file that meets the requirements of the destination at an acceptable size and appearance.
First compare the dimensions and confirm that you exported the image you intended. Then test a lower quality setting or a smaller width if either is acceptable. If the existing PNG is lighter and the site accepts it, keep the PNG for that asset. A mixed set of formats can make sense when each asset has a different job.
Check animated PNGs separately
An animated PNG contains a sequence of frames. Convertly's image conversion draws a decoded image onto one canvas and exports that canvas. This workflow creates a still WebP. If the animation matters, keep the animated original and use a workflow that explicitly supports converting all frames and preserving timing.
The same distinction applies when someone says a picture is moving in a preview. Determine whether the motion is part of the file or an effect applied by the website. For a still image that only moves because the page animates its container, converting the picture can be fine. The page's motion effect is controlled separately.
Replace the original carefully
Keep an editable copy of the source and add the WebP as a separate delivery file. When replacing an image on a page, change the reference to the WebP, then load the page and check that the image appears on the intended device sizes. Confirm the image is served at the correct address and still has suitable alternative text if it conveys information.
Check the final size against the problem that started the conversion. If you needed to fit under an upload limit, confirm the file is below the limit with some margin. If you wanted a lighter page, compare the bytes actually delivered to a visitor. The exported file size is a useful measurement, while the page test shows whether the new asset is being used.