It depends whether the node is fully synced or not, and what services are running on the node (core, horizon, history etc). You see, nodes can be setup to retain information for only latest N ledgers.
Approximate numbers:
- Fully synced horizon db is ~ 12-15GB
- Fully syncedcore db is ~ 7-10GB
Nodes also retain some buckets, archives with immutable ledger data in XDR format. Moreover, nodes with enabled history role store full ledger history archives and descriptor files in JSON format ("table of contents" for each archive with unique hash).
So the storage size may vary depending on the deployed services and settings.
