Verdict
Built from the measurements below
- Accuracy is too close to call: Ministral 3 3B 2512 scored 26.2% and Mistral Medium 3.5 28.8% on the same 80 questions, a gap within what chance alone could produce.
- Ministral 3 3B 2512 is 128× cheaper per question as billed ($0.00019 vs $0.025), reasoning tokens included.
- Ministral 3 3B 2512 generates text 1.7× faster: 252 tokens per second against 145.
- Ministral 3 3B 2512 starts answering sooner: 0.3 s to the first token, against 0.5 s for Mistral Medium 3.5.
- Mistral Medium 3.5 accepts more context: 262k tokens against 131k.
Which should you choose?
Choose Ministral 3 3B 2512 for the lower cost per correct answer ($0.00074 against $0.087), faster streaming, a quicker first token, shorter outputs (about 1,652 tokens per question against 3,268) and open weights you can run yourself. Choose Mistral Medium 3.5 for a 262k-token context window. The widest subject gap is in economics: Mistral Medium 3.5 answered 6 of 9 correctly, Ministral 3 3B 2512 4 of 9. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap -2.5 points (z = -0.35). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.