How much storage does a digitized family collection need?
As rough master-file rules: a 600 PPI scan of a 4 × 6 print is about 26 MB, an hour of 10 Mbps video capture about 4.5 GB, and an hour of CD-quality WAV about 0.64 GB. Multiply by your counts, then by two or three protected copies — most family collections land between 100 GB and 2 TB.
What this planner calculates — and what it does not
The arithmetic is straightforward once the collection is inventoried. Still-image storage is the number of items multiplied by the master file size. Video and audio storage are recorded hours multiplied by the size produced per captured hour. The protected total is the master set multiplied by the number of independent copies you intend to keep.
Protected storage = (still-image GB + video GB + audio GB) × number of copies
The uncertain part is not the multiplication. It is the rate supplied to it. A compressed video file can be much smaller than an uncompressed capture, two scanners can take very different times at the same nominal resolution, and fragile material needs more handling. That is why each rate is visible and editable instead of hidden behind a claim of precision.
How to replace the starting assumptions
Run a small representative test before committing to the entire project. Scan ten typical photos using the settings you plan to keep, then divide their combined file size and elapsed time by ten. Capture ten minutes from a typical video or audio tape and inspect the resulting file size. Enter those measured rates above. This turns a broad planning estimate into a forecast for your equipment and workflow without uploading any family material.
For VHS, capture normally occurs in real time. The District of Columbia Public Library’s Memory Lab advises allowing additional time for encoding, describing, and saving the result, while its compressed workflow produces a much smaller access file than the initial capture. The defaults here are deliberately editable because equipment and preservation goals differ.
Why the calculator separates masters from copies
A large drive is not automatically a backup. The “one master set” line answers how large the completed collection is. The protected line answers how much total capacity is required across all copies. If every copy sits on the same physical drive, one failure can still remove all of them. Keep independent copies on separate devices and, where practical, in separate locations.
Sources and calculation status
The video starting point is consistent with the DC Public Library Memory Lab’s compressed planning figure of roughly 4 GB per captured hour. The 1.04 GB audio starting point corresponds to one hour of 48 kHz, 24-bit stereo PCM audio, calculated from sample rate × bit depth × channels × time. Both rates remain editable.
Primary references: DC Public Library Memory Lab transfer guides; Canadian Heritage Information Network audio digitization guide. Links are provided for methodology, not endorsement.
Frequently asked questions
Should I use the maximum DPI offered by my scanner?
Not automatically. Higher PPI creates more pixels and larger files, but a scanner’s advertised setting can exceed its useful optical detail. Choose a target based on the original size and intended print or preservation use, then test a representative item. Use the film scan calculator to see the pixel and storage consequences before scanning a collection.
Does three copies mean I need one drive three times as large?
No. It means the total capacity across independent destinations must be three times the master set. Three copies on one physical drive do not protect against that drive failing.
Can I use this to compare DIY with a digitization service?
Yes. Use the work-hours result to understand the DIY commitment, then compare it with itemized service quotes. Do not compare only the headline price: confirm the delivered resolution, format, compression, naming, media return policy, and whether master files are included.
What should I do with damaged or mouldy tapes?
Do not use this calculator as a handling guide. Physical condition is outside its scope. Media that is mouldy, brittle, shedding, or irreplaceable should be assessed by a qualified preservation or transfer professional before playback.
Related tools: calculate a specific still-image master with the film scan calculator, or model a tape capture with the VHS digitization calculator.