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Why is my JPEG bigger in KB after I added a watermark?

Because the tool cannot add a mark without saving the photo again, and it saves JPEG at quality 92. If your original was saved at a lower quality, say a photo that went through WhatsApp or a compressor, the new file can come out larger in KB even though its dimensions are identical. If you need it smaller, compress the result after watermarking.

Published · 3 min read

The dimensions did not change, the save did

A 1600 × 1200 photo leaves the tool at 1600 × 1200. But the size of a JPEG file is not set by its dimensions alone; it depends on the quality it was saved at. The original file does not carry its compression 'recipe' with it, so when the mark is drawn and the photo saved again, the tool always uses quality 92, a high setting that keeps detail and crisp letter edges.

If the original was saved at quality 70, for example, saving at 92 means a heavier file, full stop. The higher quality does not bring back detail lost in the first compression; it just records the photo as it now is, more faithfully.

A second reason: the mark is new detail

JPEG squeezes calm areas like a white background very easily and spends more bytes on sharp edges. A watermark is letters with clear edges, and an outline adds even more edge. One mark in a corner adds little; a repeated pattern over a white background can add a noticeable amount.

How to check, and what to do

  1. After downloading from the Image watermark editor tool, a message shows the file name, dimensions and size. Compare it with the original.
  2. If the size is fine for your store, leave it; the difference is usually not worth another save.
  3. If you need smaller files, run the watermarked photos through the Image compressor at a lower quality, and check the mark's letters after compressing.
  4. Always keep your original, unmarked photo: it is what you start from if you change the mark later.

What about PNG and WebP?

  • WebP is also saved at quality 92, so the same applies to it.
  • PNG is saved lossless, so there is no quality setting to be higher or lower. Its size changes only with the detail the mark adds.
  • The tool never changes the format: JPEG stays JPEG and PNG stays PNG.

In short, the bigger file is not a mistake and does not mean the photo was damaged. It is a high quality save of a photo that had been compressed hard, and if size matters, compression is a separate last step.

Common questions

Can I pick the save quality inside the watermark tool?

No, it is fixed at 92 for JPEG and WebP. For control over quality, use the compressor after watermarking.

Does adding a watermark lower the photo's quality?

Re-saving a JPEG loses a little, but quality 92 is high and the difference is usually invisible.

Should I compress before or after watermarking?

After. Compressing first is wasted, because the tool saves again at quality 92 anyway.