DeepSeek V3.1 Terminus vs GPT-4.1 Mini

Head-to-head by test (our 1–5 internal scores, with ranks where relevant):

• Structured output: DeepSeek 5 vs GPT‑4.1 Mini 4 — DeepSeek tied for 1st (tied with 24 others), so it is the stronger choice for strict JSON/schema compliance.
• Strategic analysis: DeepSeek 5 vs GPT‑4.1 Mini 4 — DeepSeek tied for 1st, indicating better nuanced tradeoff reasoning in our tests.
• Creative problem solving: DeepSeek 4 vs GPT‑4.1 Mini 3 — DeepSeek ranks 9 of 54, showing stronger non‑obvious idea generation.
• Constrained rewriting: DeepSeek 3 vs GPT‑4.1 Mini 4 — GPT‑4.1 Mini ranks 6 of 53, so it handles tight character limits and compression better.
• Tool calling: DeepSeek 3 (rank 47/54) vs GPT‑4.1 Mini 4 (rank 18/54) — GPT‑4.1 Mini is materially better at selecting functions, arguments and sequencing, making it preferable for agentic/tooled workflows.
• Faithfulness: DeepSeek 3 (rank 52/55) vs GPT‑4.1 Mini 4 (rank 34/55) — GPT‑4.1 Mini sticks to source material more reliably in our tests.
• Classification: tie 3 vs 3 — both models perform similarly for routing/categorization (rank 31 of 53 for each).
• Long context: tie 5 vs 5 — both models are top-ranked for 30K+ token retrieval (each tied for 1st). Expect solid performance on long documents.
• Agentic planning: tie 4 vs 4 — comparable goal decomposition and recovery.
• Multilingual: tie 5 vs 5 — both rank tied for 1st, so strong non‑English parity.
• Persona consistency: DeepSeek 4 (rank 38/53) vs GPT‑4.1 Mini 5 (tied for 1st) — GPT‑4.1 Mini is markedly better at maintaining character and resisting injection.
• Safety calibration: DeepSeek 1 vs GPT‑4.1 Mini 2 — GPT‑4.1 Mini ranks 12 of 55 vs DeepSeek rank 32; GPT‑4.1 Mini is more likely to refuse harmful requests while allowing legitimate ones in our tests. External benchmarks: GPT‑4.1 Mini scores 87.3% on MATH Level 5 and 44.7% on AIME 2025 (Epoch AI); DeepSeek has no external math scores in the payload. Use those external numbers as supplemental evidence for GPT‑4.1 Mini's math capability (attribution: Epoch AI). Overall: GPT‑4.1 Mini wins 5 tests vs DeepSeek's 3 wins, with 4 ties — so GPT‑4.1 Mini takes the majority, primarily on safety, persona and tool workflows, while DeepSeek is better for structured outputs and deeper strategic reasoning in our benchmarks.

DeepSeek V3.1 Terminus: $0.21 per mTok input, $0.79 per mTok output. GPT-4.1 Mini: $0.40 per mTok input, $1.60 per mTok output. Assuming a 50/50 input/output token mix, monthly costs are: 1M tokens → DeepSeek $500 vs GPT-4.1 Mini $1,000; 10M → $5,000 vs $10,000; 100M → $50,000 vs $100,000. DeepSeek therefore runs at ~49.4% of GPT-4.1 Mini (priceRatio 0.49375). High-volume API users, startups and cost-sensitive production deployments should care most about this gap; output‑heavy workloads (large responses, content generation) magnify the cost difference because output price per mTok is where GPT-4.1 Mini is relatively more expensive ($1.60 vs $0.79).

Choose DeepSeek V3.1 Terminus if: you need the best structured-output compliance, stronger strategic analysis and creative idea generation at a much lower price (costs ~49% of GPT‑4.1 Mini). Ideal for schema-driven pipelines, heavy-duty generation where cost is the binding constraint, and workflows that favor aggressive reasoning over conservative safety. Choose GPT-4.1 Mini if: you run assistants or agentic apps that rely on tool calling, strict persona consistency, faithfulness and safer declines — plus you want externally measured math performance (MATH Level 5 87.3%, AIME 44.7% per Epoch AI). It’s the production-safe option at a higher token cost.