PNG vs WEBP vs JPG for cutouts: which format keeps transparency

After removing a background, you have to choose a file format. The choice decides whether the transparency survives, how large the file is, and which apps can open it. Pick the wrong one and you get a black or white box where the background used to be, or a file too large to upload. This guide explains how the three formats offered by the tool differ and gives a simple rule for choosing.

What transparency actually is

A normal color image stores three values per pixel: red, green, and blue. An image with transparency stores a fourth value, alpha, which says how opaque the pixel is, from fully transparent (0) to fully opaque (255). Values in between are partially transparent, which is what makes soft edges such as hair blend smoothly into whatever background you later place them on.

A background remover produces exactly this alpha channel. Whether you keep it depends on the format you save in.

PNG: lossless and transparent

PNG stores every pixel exactly, with a full alpha channel. Nothing is thrown away, and you can open and re-save it as often as you like without loss.

Strengths: perfect transparency including soft edges; lossless quality; supported everywhere: every browser, operating system, design app, office suite, and marketplace.

Weakness: size. A photo saved as PNG is typically several times larger than the same photo as JPG, because lossless compression is much less efficient on photographic detail. A 12-megapixel cutout can easily be 10 to 20MB as PNG.

Use PNG for: logos, signatures, stickers, anything going into a design tool, and any cutout you will edit further.

WEBP: small and transparent

WEBP, developed by Google, supports both lossy compression (like JPG) and an alpha channel (like PNG). A lossy WEBP with transparency is usually far smaller than the equivalent PNG, by 85 to 91% on the photo cutouts we measured, while looking nearly identical at normal viewing sizes.

Strengths: transparency at a fraction of PNG's size; supported by all modern browsers; ideal for websites.

Weaknesses: some older desktop software, older versions of office suites, and some print services and marketplaces do not accept it. It is also lossy at the quality levels that make it small, so it is not ideal as a master file you will keep editing.

Use WEBP for: cutouts on your own website or online store (Shopify accepts it), and anywhere file size matters and you have confirmed WEBP is supported.

JPG: small, universal, no transparency

JPG (or JPEG) is the most widely supported photo format, and very efficient for photos. But it has no alpha channel at all. When you save a cutout as JPG, transparent areas must be filled with a solid color.

Strengths: small files; accepted everywhere, including every marketplace and print service.

Weaknesses: no transparency; lossy, so repeated re-saving gradually degrades quality.

Use JPG for: final product photos on white or a solid color, passport and ID photos, and anywhere a solid background is wanted.

What happens when transparency is lost

If a transparent image is converted to a format without alpha, or opened in an app that ignores alpha, the transparent pixels have to become some color. Depending on the software, they turn white, black, or sometimes show leftover colors that were hidden behind the transparency. This is why a cutout saved as JPG by another app can arrive with a black background.

The tool avoids this by making you choose: when you export JPG, it composites the cutout onto the background color you picked (white by default), so you always know what color the empty areas will be.

Side by side

What we measured

We saved each of the six example cutouts at full size in all three formats, using the tool's default quality of 92 for WEBP and JPG (JPG on a white background):

WEBP kept full transparency at between a tenth and a seventh of PNG's size, and JPG was smaller still without transparency. PNG sizes varied the most: detailed hair and fur compress poorly without loss. These were encoded with the libvips library, so your browser's downloads will differ a little in size, but the proportions hold. More in our test results.

A simple rule

• Need transparency and will edit or design with it? PNG.
• Need transparency on a website and want it light? WEBP.
• Want a solid background (white or a color)? JPG.

When unsure, export a PNG first and keep it as your master. You can always produce a WEBP or JPG from it later, but you cannot recover transparency from a JPG.

Notes on resolution and color

On a computer, all three exports keep your original image's width and height by default (phones and low-memory devices scale photos above about 4 megapixels down before processing). Cropping or a marketplace preset changes the dimensions, not the format's quality. The exports are in the standard sRGB color space used on the web, which is what marketplaces and browsers expect. If you are preparing images for professional print that requires CMYK, convert them in a print-focused tool afterwards.

Summary

PNG keeps perfect transparency at the cost of size; WEBP keeps transparency in a much smaller file but is less universally accepted; JPG is small and accepted everywhere but cannot be transparent. Keep a PNG master of any cutout you care about, export WEBP for your own website, and JPG on a solid background for marketplaces and official photos.