The short answer: use PNG for a reusable cutout
Use a transparent PNG when you need to place a subject over different backgrounds. JPEG cannot store transparency. WebP can store transparency and often offers smaller files, but support for importing and exporting it varies across design tools and publishing systems.
Cutout Lab accepts JPEG, PNG, and WebP uploads and offers all three as download formats. Choose PNG or WebP for transparency; JPG produces an opaque image. You do not need to convert a good JPEG source to PNG before removing its background. Changing the input file extension does not remove anything.
| Format | Transparency and compression | Useful role |
|---|---|---|
| PNG | Supports alpha; lossless compression | Reusable cutout master or a handoff to a design editor. |
| JPEG | No alpha; typical photo workflows use lossy compression | Finished photograph with a deliberately chosen opaque background. |
| WebP | Supports alpha; lossy or lossless encoding | Transparent or opaque website delivery copy when the publishing workflow supports it. |
PNG: transparency and lossless image storage
PNG stores image data with lossless compression and supports an alpha channel for fully or partially transparent pixels. That makes it useful for a cutout master, layered artwork, and edges that must blend into different backgrounds. Lossless storage preserves the pixels you export; it does not repair flaws already present in the source.
Detailed photographs can produce large PNG files. A PNG with a solid white background is still opaque, so the format alone does not prove that a background was removed. In Cutout Lab, select Transparent before downloading and verify the file over a colored layer.
JPEG: compact photos with an opaque background
JPEG is widely supported and useful for photographs that already have a finished background. Its lossy compression can reduce file size substantially, but strong compression can create blockiness and ringing around high-contrast outlines. Start from the best available original instead of a repeatedly re-saved copy.
When a transparent cutout is converted to JPEG, it must be flattened onto a solid background. Choose that background deliberately in a destination editor. JPEG cannot keep an invisible area for later placement, even when its filename or an upload label describes it as a cutout.
WebP: a delivery option for website images
WebP supports lossy and lossless compression as well as transparency. It can be useful for delivering cutouts on a website when the publishing workflow supports it. Compare actual output files: the smallest format depends on the image, encoder settings, and acceptable quality.
Select WebP in Cutout Lab's format controls to download a delivery copy. Keep Transparent selected if you need alpha, and retain a PNG master for later editing. Check the downloaded WebP in the destination: support in a browser does not guarantee that a document editor or upload portal accepts it.
Worked handoff: one product, three destinations
Suppose the same product needs a catalog image, a colored social layout, and a website thumbnail. Start with one refined transparent PNG. For the catalog, place that master over the required background in a destination editor and export the accepted format. For the social layout, reuse the untouched master so a white rectangle does not cover the design. For the website, create a delivery copy at the actual required dimensions and compare WebP with the alternatives your pipeline supports.
These are three outputs from one master, not three removal jobs. Keep filenames that distinguish the versions, for example product-master.png, product-white.jpg, and product-thumbnail.webp. Renaming an extension is not conversion, and saving a JPEG as PNG does not restore transparency or detail that the JPEG never contained.
Make a fair file-size comparison
Resize each candidate to the same dimensions and compare the same composition. A transparent PNG and a JPEG with a white background are not interchangeable results, even when their thumbnails look similar on a white page. For lossy files, inspect text, edges, and texture rather than assuming matching quality-slider numbers represent equal visual quality across formats.
Record the actual byte sizes after export. There is no universal compression percentage for your particular cutout: large empty regions, fine hair, noise, and texture compress differently. Keep the smallest delivery file that preserves the appearance and transparency you need, while retaining the original PNG master for future work.
Check dimensions, file size, and destination rules
File format and pixel dimensions solve different problems. A compressed photo can still exceed the editor's 40-megapixel limit, and a detailed image under that limit can still exceed 25 MB. Resize to reduce dimensions and adjust compression or format to reduce file size, checking quality after each change.
For a listing, social post, or website, check the destination's accepted formats and dimensions before publishing. Keep a transparent master even when the destination requires a white-background JPEG. This avoids repeating removal when another design later needs the same subject.
Format references
The format capabilities summarized here are documented in MDN's image-format guide and Google's WebP container specification. Format support is separate from Cutout Lab's own upload and export choices; a format supporting animation does not mean this editor accepts animated files.