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Quick Start

1
Click on the selection panel to select images, or drag and drop images/folders into itselect images
2
Adjust the image compression optionsimage options
3
Press Compress to startcompress
4
View compression results and open files in Finderresults

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Compression Options

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Image Quality

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Target File Size

Choose Target file size to compress images to an exact size instead of a quality level. Enter the size and pick KB, MB, or GB (default 200 KB).
  • Output is always saved as JPG, so the Image format picker is locked while this option is selected
  • Compresto lowers the quality step by step until the file fits
  • If an image can’t get small enough, Compresto keeps the smallest version it could make and shows Couldn’t reach target size next to that file
Target file size is available in the main window, presets, and per-file settings. Drop Zone, folder monitoring, and deep links use quality levels instead.

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Image Size

Resize images during compression:
When resizing, aspect ratio is always preserved.

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Image Format

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Supported Input Formats

Compresto supports compressing these image formats:
  • JPG / JPEG
  • PNG
  • WebP
  • AVIF
  • HEIC / HEIF
  • DNG
  • TIFF
  • BMP
  • SVG (converted to JPG or PNG)
Animated GIFs have their own options — see How to compress GIF.
JPEG and PNG output keeps the original print resolution (DPI), so compressed images place at the same size in layout apps. See File metadata.

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Tips for Best Results

  • For photos: Use JPG format with “Good” or “High” quality
  • For graphics with transparency: Use PNG or WebP format
  • For web optimization: Use WebP format with “Good” quality
  • For maximum compression: Use AVIF format (check browser support)
  • For batch resizing: Use “Max long edge” to uniformly resize images
  • For strict upload limits: Use “Target file size” to guarantee the file fits