How much space can my Mac reclaim?
Answer 4 quick questions for an estimate (not a real scan). For the real number, download Atlas — it's the tool that actually reads your disk.
Do you run any of these disk-hungry tools?
Estimated reclaimable – GB Conservative cap: no more than 50% of used space.
Method
Estimate = years × 2GB (accumulated caches/logs/temp) + disk-pressure term (~4% of used) + per-tool typicals (Xcode ≈ 8GB, Node ≈ 2GB, Homebrew ≈ 1.5GB, downloads/logs ≈ 0.5GB). This is a static heuristic, not your machine's measured value; Atlas's real scan is authoritative.