"Just get more RAM" isn't always the right answer
RAM and storage get lumped together in buying advice, but they solve completely different problems. RAM is short-term working space — run out, and everything open at once slows down or starts swapping to disk. Storage is long-term space — run out, and you simply can't save anything new. Sizing one doesn't tell you anything about the other.
Most spec sheets just say "16GB RAM, 512GB SSD" without explaining whether that fits how you'll actually use the machine. This calculator works backwards from your real workload instead — either a quick use-case pick, or the actual apps, tabs and files you deal with day to day.
Two calculators, one straight answer
The RAM Calculator either takes a quick use-case (Gaming, Video Editing, Everyday Multitasking...) or lets you tick the exact apps you run — Photoshop, Discord, a dozen Chrome tabs, a virtual machine — and adds them up against a realistic overhead for your operating system.
The Storage Calculator works the same way for disk space: games installed, photos and RAW files, hours of 4K footage, offline music — summed up with a healthy free-space buffer so your drive doesn't run at 100% capacity.