JPG-Compression and File Size

The following table illustrates the file sizes for the images used before, resolution of the full pictures is 10 megapixels.

There is no common standard how the level of JPG compression is quantified. Photoshop uses a scale from 0 to 12, other programs may have a scale up to 100 and cameras have usually just two or three levels with symbols or names, no figures at all.

Accordingly you may need to use different values in your favorite software to produce similar results; mine are based on a range from 20 to 100.

image quality file size comment file size of sample images in MB
uncompressed

file size without JPG compression

for comparison: Bitmap format (.bmp) 29,4 MB
best JPG quality

file size at JPG quality 100

see section „best possible JPG quality“

JPG quality: 100
11,9 / 17,1 MB
good JPG quality

file size at JPG quality 80

see section „color shift“

JPG quality: 80
1,6 / 2,5 MB
medium JPG quality

file size at JPG quality 50

see section „JPG artifacts“

JPG quality: 50
0,9 / 1,5 MB
lowest JPG quality

file size at JPG quality 20

see section „square shaped blocks and loss of details“

JPG quality: 20
0,5 / 0,8 MB

For comparison: When using the PNG format which is very popular for lossless compression there would be files of about 15 and almost 20 MB left.