Why Is My Compressed Image Bigger Than the Original?

Check format, quality and dimensions when image compression makes a larger file. Compare actual output bytes and preserve the original when the result is worse.

Compression is a new encoding, not a size guarantee

An image compressor decodes pixels and writes another encoded file. The original may already be efficiently compressed. Choosing a different format, a higher quality or lossless output can produce more bytes even when the picture looks unchanged.

File size and pixel dimensions are different measurements. A 1200 × 800 image can have several file sizes depending on its contents and encoding. A flat icon behaves differently from a photograph with noise and fine texture. Compare the actual original and output bytes instead of assuming that pressing Compress must make the file smaller.

Check the output format first

Converting a compact JPEG photograph into PNG can increase size because PNG encodes the decoded pixels differently. A quality slider is meaningful only for formats and encoders that use it; browser canvas export does not apply a JPEG-style quality choice to PNG in the same way. See MDN’s image export reference.

For a photo, try an appropriate JPEG or WebP quality and compare detail. For a graphic that needs transparency, test PNG or supported WebP output instead of discarding the alpha channel just to chase a smaller number. The transparency guide explains that separate tradeoff.

Change one setting and inspect a new result

In the image compressor, start with one synthetic or non-sensitive image. Compare quality-based output with a target-size attempt. If resizing is allowed, confirm that the resulting dimensions still meet the destination’s needs. Reaching a byte target by shrinking the image may make small text illegible.

A target can be unattainable under the selected constraints. Review any unmet-target notice and inspect the actual result size. Do not describe a file as under a limit until the saved output is measured. The tool’s preview or a started download does not prove the final file was saved to your device.

Keep the better source when there is no improvement

Compare a detailed area, text edges and gradients at full resolution. If the new version is larger without a needed format change or visible benefit, keep the original. Repeatedly recompressing the last JPEG can add artifacts; start comparisons from the same original instead.

Use the photo resizer when pixel dimensions are the real requirement, or the photo converter when a destination accepts only a particular format. Neither a smaller file nor a successful upload proves that metadata was removed, an AI label will disappear or the image is suitable for every platform.