Generally, a RAW file will be between two and six times larger than a JPEG file. RAW files are bigger because they contain a much greater amount of image data. A JPEG image is essentially all that data compressed down into a smaller file size that’s easier to share.
Going from a RAW file to a JPEG will affect quality because you’re converting to a lossy format. RAW files contain a high amount of detail — converting to a JPEG means compressing the details into a much smaller file size with less space to store image data.
Many professional photographers shoot in RAW because the format captures the highest level of detail. It can often be easier to edit exposure later with a RAW file. However, shooting in JPEG has its benefits, since their smaller file sizes allow you to shoot more images at once and transfer files faster.
Depending on the camera you use, shooting in RAW may sometimes cause the files to show up as JPEGS by default. The original RAW file should still be there though. On your camera settings in the editing mode, choose the option to “Use RAW as original,” if possible.
RAW + JPEG mode is available on some digital cameras, and lets you shoot and save in both file formats at the same time. This saves two copies — the original RAW file and a JPEG. This lets you preview and use a JPEG image immediately — but uses up more memory since you have two files for just one image.