Using the tool to make a decision
Photo Archive Growth Planner: inputs, worked examples and limits.
Make the choice with your own constraints
Method and sources
Check the formula, units and reference material.
Choose a growth model before buying storage
Measure one current archive, in a consistent unit, before estimating growth. Include the files you intend to keep, such as RAW originals and edited exports. Count extra copies separately. A plan for one library is not a plan for every backup copy.
Existing drive, monthly cloud, or annual cloud?
List current free space, existing paid storage, and whether you need access away from home. If your present setup meets the capacity and access requirements, buying another subscription may not solve a real problem.