JPEG or PNG? Compare text, texture and transparency

Choose PNG when an image needs a transparent background or contains small text, labels, or other edges you want to preserve exactly. Choose JPEG when you have a textured image and a smaller upload matters more than keeping every original pixel. Our textured source shrank from 1,531,117 bytes to 233,215 bytes as JPEG. For a plain interface image with sharp text, the PNG was smaller: 30,546 bytes versus 81,823 bytes for JPEG.

JPEG uses lossy compression and does not support transparency; PNG uses lossless compression and supports transparency. Those properties are more useful than a rule based only on whether a file is called a “photo” or a “graphic.”

Texture: check the bytes as well as the dimensions

This original synthetic scene is 1200 × 900 pixels in both versions. Its PNG source is 1,531,117 bytes; the JPEG version is 233,215 bytes. That is a saving of 1,297,902 bytes for this particular image.

Open the two files and compare the parts you care about at the size your recipient will see. JPEG reaches its smaller size by discarding image information. A conversion cannot promise that every texture or edge will look the same, and these file sizes do not establish a quality ranking for other images.

The dimensions also explain a common upload surprise. Both files are 1200 pixels wide. Width tells you how many pixels the image contains across a row; the byte count tells you how much data the file occupies. A form can accept the dimensions and still reject the file size.

Text: PNG can be the smaller choice

The second pair has a plain background and sharp interface text. Here, the original PNG is 30,546 bytes, while the JPEG export is 81,823 bytes. Both are 1200 × 700 pixels. In this case, PNG is 51,277 bytes smaller.

For a labeled diagram, screenshot-like graphic, or image with text annotations, PNG is a useful first export: its lossless encoding keeps the exported pixel values intact. Compare the files at the size they will actually be shared. These examples did not include an OCR or readability study, so their byte counts cannot tell you which text another person will find easier to read.

Keep a PNG copy if you expect to add or revise annotations. Exporting a JPEG and later saving it as PNG preserves the pixels in that JPEG; it cannot recover information the JPEG export already discarded. Repeated JPEG exports can introduce further loss.

Transparency: JPEG needs a background

The badge pair makes the format difference concrete. The transparent PNG badge is 4,549 bytes and uses an alpha channel. Its top-left pixel has alpha 0, meaning it is fully transparent. The artwork also includes a partially transparent fill. The JPEG badge is 10,693 bytes, has no alpha channel, and has a white top-left pixel.

For this JPEG, white was deliberately placed behind the badge before encoding. White is not a background that JPEG automatically chooses. If the badge must sit over a colored page, slide, or profile banner and let that color show through, upload the PNG. If you want a fixed white rectangle behind it, the JPEG version has one. Both badge files are 500 × 250 pixels, but only one retains transparency.

Pick a file for the upload you have

Suppose a form sets a 500,000-byte maximum and accepts either JPEG or PNG. The textured scene’s 1,531,117-byte PNG exceeds that limit, while its 233,215-byte JPEG fits. The two interface files both fit, and the PNG is smaller. That is a reason to check the actual file against the form’s limit instead of assuming JPEG is always the compact option.

For a transparent graphic, check the format rule first. An upload that accepts only JPEG requires an opaque background, even if your source PNG has transparent corners. Choose that background deliberately when exporting. For a screenshot with labels, start with PNG and change dimensions only after checking which labels must remain readable.

A small file can still fail a dimension rule. The badge PNG is only 4,549 bytes, but its width is 500 pixels. A form requiring at least 1,200 pixels would reject its dimensions even with a 500,000-byte allowance. Conversely, a fictional 5,000-byte limit would accept that PNG by size and reject the 10,693-byte JPEG. Accepted format, width and bytes are separate requirements; use the saved file’s values for each.

Changing a filename from .png to .jpg does not convert its image data. Export or convert the image into the requested format, then inspect the new file. An upload service may also process an image after submission, so the result you share or publish is the final check when that result is available.

Source note: These are original synthetic HowCurio images measured with Pillow 12.3.0, not camera photos or captures from Photos or Snipping Tool. A recorded Chrome 154 check confirmed that the JPEG scene fixture loaded at 1200 × 900 pixels; it did not test visual quality, OCR, conversions in those apps, or an upload service. The JPEG examples were encoded with a quality setting of 80, which is an encoder setting rather than a cross-format measure of visual quality.