Photo Storage Calculator

Photo storage sizing helps photographers plan memory card capacity, hard drive purchases, cloud storage subscriptions, and backup strategies. File sizes vary enormously by camera resolution, format (RAW vs. JPEG), compression level, and scene complexity.

File size estimation formulas:

RAW file size (approximate): RAW Size (MB) ≈ Megapixels × Bits per Pixel ÷ 8 × Compression Factor Typical compression factor for RAW: 0.5–0.7 (lossless compression)

Megapixels already counts in millions, so dividing by eight takes you straight from bits to megabytes with no further conversion. A 24 MP camera writing 14-bit RAW is 24 × 14 ÷ 8 = 42 MB before compression, and about 29 MB after lossless compression at 0.7. The calculator uses a flat 1.2 MB per megapixel, which lands on 28.8 MB for the same camera.

JPEG file size (approximate): JPEG Size (MB) ≈ Megapixels × 3 bytes × Compression Ratio Compression ratio: High quality = 0.08–0.12, Medium = 0.04–0.07, Low = 0.02–0.03

Three bytes is one uncompressed 8-bit pixel across red, green and blue, so 24 MP is 72 MB before the encoder touches it. A high-quality JPEG off that sensor is 7 to 9 MB, which is where those ratios come from. If a compression ratio above about 0.15 looks right to you, check the arithmetic: it would make the JPEG larger than the RAW file.

Typical file sizes by camera sensor:

Storage capacity formula: Photos per GB = 1,024 MB ÷ Average File Size (MB)

That uses binary gigabytes, which is what your operating system reports. Drive manufacturers count in decimal, so a drive sold as 1 TB shows up as 931 GB in Finder or Explorer. The calculator below uses the binary figure throughout, so its numbers match what you actually see when you look at the disk.

Shooting session estimate: Storage Needed = Photos per Session × Average File Size

Worked example: A wedding photographer shoots 1,200 frames with a 45 MP full-frame camera, RAW + JPEG. RAW per image: 45 × 1.2 = 54 MB. JPEG per image: 45 × 0.3 = 13.5 MB. Total per image: 67.5 MB. Session storage = 1,200 × 67.5 MB = 81,000 MB = 79 GB per wedding

Annual storage across 25 weddings: 25 × 79 GB = 1,978 GB, near enough 2 TB Under the 3-2-1 backup rule (3 copies, 2 media types, 1 offsite): 6 TB of drives to hold it.

Memory card planning

The binary gigabyte is the wrong unit here, and it is an easy mistake to make because everything above uses it. A card sold as 128 GB holds 128 billion bytes, which is 119 binary gigabytes, and formatting takes a little more off the top. Count it as 128 × 1,024 MB and 54 MB RAW files come out at 2,427 frames. Count the capacity the card actually has and it is 2,204. Nine per cent is enough to matter when the question is whether one card covers a wedding day, so plan on the smaller number. The memory card capacity calculator on this site uses 93% of the printed figure for the same reason.

Everywhere else on this page the binary gigabyte is right, because the monthly and annual totals are what your operating system will report on a drive you already own.