Manufacturer’s spec sheet is your best bet.

Check the exact model number on the manufacturer’s website — BIOS won’t tell you.

BIOS will show you total RAM and maybe how many slots are used, but it can’t tell you whether those slots are actual sockets or just soldered chips. Same with Windows’ Task Manager or system info. They report capacity, not construction.

The manufacturer’s specs page (or the PDF service manual) will explicitly say “onboard memory” or “SO-DIMM slots” or “soldered.” If it says “2 slots” and those slots are listed as upgradeable, you’re good. If it says “8GB LPDDR4 (onboard)” you’re stuck.

Some third-party tools like CPU-Z will show you the number of RAM “slots” detected, but if a soldered stick is in slot 0 and slot 1 is empty, it still shows as two slots. That can fool you — the empty slot might not actually exist.

Don’t trust generic “max memory” specs on retailer sites either. They’re often copy-pasted and wrong. Find the exact model number — usually on a sticker on the bottom — and go straight to Lenovo, Dell, HP, or whoever made it.