DeepSeek V4 Flash vs GPT-5.4 nano

Pick GPT-5.4 nano if you want the stronger benchmark profile. DeepSeek V4 Flash only becomes the better choice if agentic is the priority or you want the cheaper token bill.

GPT-5.4 nano has the cleaner provisional overall profile here, landing at 61 versus 59. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

GPT-5.4 nano's sharpest advantage is in knowledge, where it averages 53.2 against 45.2. The single biggest benchmark swing on the page is HLE, 8.1% to 37.7%. DeepSeek V4 Flash does hit back in agentic, so the answer changes if that is the part of the workload you care about most.

GPT-5.4 nano is also the more expensive model on tokens at $0.20 input / $1.25 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash. That is roughly 4.5x on output cost alone. GPT-5.4 nano is the reasoning model in the pair, while DeepSeek V4 Flash is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. DeepSeek V4 Flash gives you the larger context window at 1M, compared with 400K for GPT-5.4 nano.