Estimate storage for your photo library.
A photo library is an accumulating archive, so the number that matters is annual growth as much as the current total. Keeping edited alongside original files adds roughly sixty percent, since edits are typically saved as full-resolution derivatives. Multiplying the total by three shows the capacity a 3-2-1 backup actually needs, which is the figure people underestimate when buying a drive.
Library size
Total GB = photos per year x years x average file size MB x copy factor / 1024
Backup capacity
Backup capacity = total library GB x 3 copies
Modern phone photos land around 3 to 8 MB, mirrorless JPEGs 8 to 15 MB, and full-frame raw files 25 to 50 MB. Check the properties of a recent batch rather than guessing.
Not for images you care about. Editing is not reversible once the original is gone, and future software will do better with the original data than with a processed derivative.