Soldered RAM looks like a flat chip. Replaceable RAM is a stick.

Open the case and look for memory modules. If you see a small, rectangular circuit board sitting at an angle in a slot—that’s removable. Usually held in by clips on each end. That’s SO-DIMM RAM.

If you see chips soldered directly to the motherboard—little black rectangles, often in pairs, flush against the board—that’s soldered. No slot, no clips. It’s not coming out.

Some laptops have one soldered and one slot. That’s the worst of both worlds.

Final thought: if it’s not obvious after ten seconds of looking, Google the model number and “RAM upgrade” before buying anything.