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I made a PNG photo smaller in dimensions, but the file barely shrank or even grew. Why?

Because 'Save as' is on 'Original format', so the picture stays a PNG, and PNG stores photographs with no loss at all, which keeps them heavy however much you shrink them. Switch 'Save as' to JPEG or WebP, set the quality, and you will see the size drop clearly in the table before downloading. Keep PNG for logos and flat graphics.

Published · 2 min read

Where the PNG came from

Plenty of product pictures arrive as PNG without anyone choosing it: a phone screenshot, an export from a design app, an image saved from a supplier's site. The file looks like any photo, but it is stored in a way that discards nothing, which is excellent for simple graphics and poor for photographs full of gradients and shadows.

What happens inside the tool

The default in the Image resizer is 'Original format', so the output is saved in the format of the file you chose. A PNG comes out as a PNG, and the quality slider does not even appear, because PNG has no quality setting. Pick JPEG and the picture is converted to JPEG, and the slider shows up.

Worked example

A PNG input with 'Save as' on 'Original format': the output is PNG.

The same file with 'Save as' on JPEG: the output is JPEG at the quality you choose, 90 by default.

The results table shows the original format, the output format and both sizes, so you see at once which one you got.

There is a second, less common cause: a heavily compressed JPEG that you save as PNG after resizing. Here the file really does grow, because PNG faithfully stores even the artifacts the earlier compression left behind.

The fix, step by step

  1. Choose the image and type the new dimensions as before.
  2. Under 'Save as', choose JPEG for an ordinary photograph.
  3. If the picture has transparent areas you want to keep, choose WebP instead, because JPEG fills them with the background color and the tool warns you.
  4. Start at quality 90, then try 80, comparing the size in the table and the preview.
  5. Download. The file name carries the new extension, so you will not confuse it with the original.

When to stay with PNG

  • Logos, icons and graphics with flat areas of color.
  • Pictures with small sharp text, such as a size chart, if smudges appear around letters after saving as JPEG.
  • Any image that needs transparency where WebP is not accepted.

Common questions

Does converting PNG to JPEG damage the picture?

JPEG gives up some fine detail depending on the quality, and on product photos you rarely notice at 80 to 90. Keep the original anyway.

The JPEG is still too heavy. What next?

Lower the quality step by step, reduce the dimensions further if they are larger than you need, or use the Image compressor.