File size when exporting photos

[ang]

I am new to Lightroom and not sure about how to change this......as a test I uploaded a couple of photos as low res, 900 pixels at 72ppi, edited them, and xported to desktop.   They have automatically been resized to 240px wide and have shrunk accordingly.  How do I keep Lightroom from changing them?

[ang]

ooops typo.......240ppi

[JohanElzenga]

PPI has nothing to do with file size. It's an instruction for the printer only and can almost always be ignored. The pixel dimensions are what counts.

[ang]

[ang]

it has gone from 189kb down to 153kb.......larger sizes come out of Lightroom even smaller!    Awkward if you need to keep them at 200kb......

[dj_paige]

It is impossible (for Lightroom Classic or any other software) to force the JPGs to be exactly 200KB. Furthermore, it doesn't make sense to set such a requirement. Trying to achieve this will cause you to perform a lot of unnecessary work, and you won't get there anyway.

Just set the proper settings in the Export dialog box, and take whatever size you get.

[elie_dinur]

The file size is smaller because in resaving the JPG in Lightroom/Export a larger amount of compression was applied, either because of a different Quality setting or because Adobe uses different JPG compression algorithms from whatever the source of the original images used. It has nothing to do with the meaningless PPI tag.

[DdeGannes]

Ok I would just like to offer the following simple explanation to the understanding of the PPI (pixels per inch). In the early 2020's I had a photo printer and began printing digital files. The first thing I learned is those computer monitors have a display resolution of 72 PPI. In the present day, computers have improved their resolution many times over.

I now have an iMac with a 5K 27" monitor and the width of the actual is 23.5" approximately.

I exported a jpeg file at 900 pixels on the long side and 72  ppi.

The exported file displays at 4" on the iMac screen when I select 100%(full resolution) see the screen capture. This indicates that the display has a max resolution in the vicinity of 400 ppi.

The actual resolution of the images is the number of pixels the "ppi" is a tag. This is further complicated by the fact that the size of the pixels also plays a part and if you are comparing a  24-megapixel sensor from a medium format camera and a 24-megapixel sensor from a mini 4/3 camera, then you are comparing "Apples and Grapes".