That all depends on what you consider to be reasonably running it. Huge RAM isn’t required to run them, that just makes them faster. I imagine technically all you'd need is a few hundred megabytes for the framework and housekeeping, but you’d have to wait for the some/most/all of the model to be read off the disk for each token it processes.

None of the closed providers talk about size, but for a reference point of the scale: Kimi K2 Thinking can spar in the big leagues with GPT-5 and such…if you compare benchmarks that use words and phrasing with very little in common with how people actually interact with them…and at FP16 you’ll need 2.9TB of memory @ 256,000 context. It seems it was recently retrained it at INT4 (not just quantized apparently) and now:

“ The smallest deployment unit for Kimi-K2-Thinking INT4 weights with 256k seqlen on mainstream H200 platform is a cluster with 8 GPUs with Tensor Parallel (TP). (https://huggingface.co/moonshotai/Kimi-K2-Thinking) “

-or-

“ 62× RTX 4090 (24GB) or 16× H100 (80GB) or 13× M3 Max (128GB) “

So ~1.1TB. Of course it can be quantized down to as dumb as you can stand, even within ~250GB (https://docs.unsloth.ai/models/kimi-k2-thinking-how-to-run-l...).

But again, that’s for speed. You can run them more-or-less straight off the disk, but (~1TB / SSD_read_speed + computation_time_per_chunk_in_RAM) = a few minutes per ~word or punctuation.