How many RAW photos fit on a memory card or drive, and how much archive space do you need?
Choose your camera resolution and a card or drive size to see how many photos fit. The second section plans a long-term archive, with backup copies and RAID overhead.
How the tool works
The tool multiplies out the capacity against a typical RAW file size for your resolution: 15 MB for 12 MP, 25 MB for 20 MP, 30 MB for 24 MP, 40 MB for 33 MP, 55 MB for 45 MP and 70 MB for 61 MP. These are rough averages for lossless compressed RAW. Real sizes vary with the camera, the scene and the ISO, so type your own average in the override box if you know it. Switch on RAW + JPEG and set the JPEG size as a percentage of the RAW to include the extra files.
Storage is sold in decimal units, where 1 GB is 1,000,000,000 bytes, but computers often report binary units, so a 128 GB card shows as about 119 GiB. The tool shows photos by the label capacity and by the capacity your computer reports, and uses the lower figure for planning. The file system takes a little more, so keep a margin.
The archive section adds up photos per year over the years you want to keep, allowing for yearly growth, and multiplies by the number of copies for the 3-2-1 rule. Usable array space is the number of drives, less one for RAID 5 or two for RAID 6, times the drive size. A mirror gives the size of one drive. RAID protects against drive failure, not against deletion or theft, so it does not replace a backup.
Questions
How many photos fit on a 128 GB card?
With 24 MP RAW files of about 30 MB, roughly 4,200 by the label capacity and about 3,970 on the capacity a computer reports. Your own files may be larger or smaller.
Why does my card show less space than the label?
The maker counts 1 GB as 1,000,000,000 bytes, while many operating systems divide by 1,073,741,824. That alone makes a card look about 7 percent smaller, before the file system takes its share.
What is the 3-2-1 backup rule?
Keep three copies of your photos, on two different kinds of storage, with one copy off site. RAID counts as one copy on one kind of storage, so it needs backups beside it.
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