Not a dedupe-engine simulator
Real backup engines differ in block sizing, compression, dedupe scope, synthetic fulls, pruning and metadata overhead.
Backup calculator
Estimate how much backup retention may consume.
Model one baseline full, daily changed-data points, periodic full restore points and the stored-size factor after compression/dedupe.
Result
Calculated values
Daily change rate matters
A 5% change rate does not mean 5% unique storage after dedupe, but it is still a useful planning input.
Periodic full assumptions are conservative
Some systems synthesize fulls without storing another complete physical copy; model the product you actually use.
Retention is about recovery
Keep restore points because they satisfy recovery objectives, then size capacity for that policy—not the other way around.