DeepSeek V3.1 Terminus vs Mistral Small 4

Across our 12-test suite, Mistral Small 4 wins 4 categories, DeepSeek V3.1 Terminus wins 3, and 5 are ties. DeepSeek wins: strategic_analysis (DeepSeek 5 vs Mistral 4) — DeepSeek is tied for 1st in strategic_analysis ("tied for 1st with 25 other models out of 54 tested"), so it's a top choice for nuanced tradeoff reasoning; classification (DeepSeek 3 vs Mistral 2) — DeepSeek ranks 31 of 53, a clear edge for routing/categorization; long_context (DeepSeek 5 vs Mistral 4) — DeepSeek is tied for 1st on long_context (tied with 36 others out of 55), meaning better retrieval accuracy at 30K+ tokens in our tests. Mistral wins: tool_calling (Mistral 4 vs DeepSeek 3) — Mistral ranks 18 of 54 for tool_calling, so it selects functions and arguments more reliably in our runs; faithfulness (Mistral 4 vs DeepSeek 3) — Mistral ranks 34 of 55, indicating fewer source deviations; safety_calibration (Mistral 2 vs DeepSeek 1) — Mistral ranks 12 of 55, better at refusals/permits; persona_consistency (Mistral 5 vs DeepSeek 4) — Mistral is tied for 1st on persona_consistency, so it resists injection and maintains character better. Ties: structured_output (both 5, tied for 1st), constrained_rewriting (3/3), creative_problem_solving (4/4, both rank 9), agentic_planning (4/4), and multilingual (5/5). Practically: choose DeepSeek when your workload is heavy on multi-hundred-thousand-token retrievals or complex numerical tradeoffs; choose Mistral when you need robust tool calling, safer refusals, and stronger alignment to sources — plus a lower per-token bill.

Per the payload, DeepSeek V3.1 Terminus charges $0.21 per mTok input and $0.79 per mTok output (combined $1.00 per mTok); Mistral Small 4 charges $0.15 input and $0.60 output (combined $0.75 per mTok). Interpreting mTok as 1,000 tokens, that means per million tokens: DeepSeek ≈ $1,000 and Mistral ≈ $750. At 1M tokens/month the delta is $250 ($1,000 vs $750); at 10M it's $2,500 ($10,000 vs $7,500); at 100M it's $25,000 ($100,000 vs $75,000). Teams with high-volume inference (10M+ tokens/month) or tight margins should prefer Mistral Small 4 for the ~25% cost saving; teams paying for specialized long-context runs or one-off high-value analyses may justify DeepSeek's premium for its long_context=5 and strategic_analysis=5 strengths.

Choose DeepSeek V3.1 Terminus if you need best-in-our-tests long-context retrieval (long_context=5, tied for 1st) and top strategic analysis (strategic_analysis=5) for large-context analytics, complex decisioning, or high-precision classification. Choose Mistral Small 4 if you prioritize lower cost (combined $0.75 per mTok vs $1.00), better tool calling (tool_calling 4 vs 3), stronger faithfulness (4 vs 3), safer refusals (safety_calibration 2 vs 1), persona consistency (5 vs 4), or multimodal inputs and a larger 262,144-token context window.