Verdict
Built from the measurements below
- Accuracy is too close to call: Gemini 3.1 Pro Preview scored 77.5% and Kimi K3.1 Pro 77.5% on the same 80 questions, a gap within what chance alone could produce.
- Kimi K3.1 Pro is 1.6× cheaper per question as billed ($0.01 vs $0.017), reasoning tokens included.
- Gemini 3.1 Pro Preview generates text 3.3× faster: 124 tokens per second against 38.
- Kimi K3.1 Pro starts answering sooner: 1.3 s to the first token, against 3.4 s for Gemini 3.1 Pro Preview.
Which should you choose?
Choose Gemini 3.1 Pro Preview for faster streaming. Choose Kimi K3.1 Pro for the lower cost per correct answer ($0.014 against $0.022) and a quicker first token.
Accuracy gap +0.0 points (z = 0.00). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.