Estimate the total
Multiply the number of images by their average file size. For example, 500 images averaging 2 MB each need about 1,000 MB, or roughly 1 GB using decimal units.
Use the image file size calculator to run your own numbers.
What affects image size?
Pixel dimensions, image detail, file format, compression level, transparency, and metadata all contribute. Two images with the same dimensions can have very different file sizes.
Plan for more than originals
Allow room for alternate sizes, thumbnails, backups, and editable source files. If your collection is important, keep a separate backup rather than relying on one storage location.
Frequently asked questions
Does a larger resolution always mean a larger file?
Not always, but more pixels often mean more data. Compression and image content can change the final size substantially.
How can I reduce the total?
Remove duplicates, resize oversized images for their actual display dimensions, and compress copies after checking quality.