Raw to Jpeg file size rule of thumb

i’m wondering if there rule-of-thumb 1 can use predict approximate size when exporting raw file in lr jpeg file.  instance, average 25 mb raw file convert 5 mb jpeg lr export quality set 100?  3.5 mb quality of 80? …

 

i know size vary, when exporting collection of raw files , have set max file size amount, lr won’t convert images because have limited file size small.  i’d able handle on sort of quality/file size relationship before start export process.

there many variables determine raw jpeg conversion efficiency. these include using loss-less raw format (i.e. cameras) versus lossy raw format (i.e. nikon), amount of detail in picture subject, , lens resolving capability (i.e. sharpness). not uncommon see 5 1 variation in jpeg file size same quality setting, camera, lens, , fstop setting. in fact way determine sharpness of lens or lens fstop setting. jpeg file size increase in proportion amount of detail captured in raw image file.

 

the more important question how jpeg compression artifacting can tolerate. typically lr quality setting of 80-90 show no visible artifacts, lower quality settings may. dependent on subject, usage , tolerance. if intend on doing additional processing of exported jpeg file suggest using setting of 90, since repeated jpeg 'file saves' cause cumulative image degradation. low resolution screen images destined web posting , no further processing quality setting of 50-70 (or less) should produce acceptable image quality.

 

the best way determine run own tests equipment , typical pictures shoot.

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