DeepSeek V3.1 Terminus vs GPT-4o

Across our 12-test suite DeepSeek V3.1 Terminus wins five tests, GPT-4o wins four, and three are ties. DeepSeek wins: long_context (5 vs 4) — DeepSeek is tied for 1st (tied with 36 others) out of 55, while GPT-4o ranks 38 of 55; structured_output (5 vs 4) — DeepSeek tied for 1st with 24 others out of 54, GPT-4o ranks 26 of 54; strategic_analysis (5 vs 2) — DeepSeek tied for 1st of 54, GPT-4o ranks 44 of 54 (important for numeric tradeoff reasoning); creative_problem_solving (4 vs 3) — DeepSeek ranks 9 of 54 vs GPT-4o rank 30; multilingual (5 vs 4) — DeepSeek tied for 1st of 55, GPT-4o rank 36. GPT-4o wins: tool_calling (4 vs 3) — GPT-4o ranks 18 of 54 vs DeepSeek 47 of 54, so GPT-4o is materially better at function selection and argument accuracy; faithfulness (4 vs 3) — GPT-4o ranks 34 of 55 vs DeepSeek 52 of 55, meaning GPT-4o sticks to source material more reliably in our tests; classification (4 vs 3) — GPT-4o is tied for 1st of 53, DeepSeek ranks 31 of 53; persona_consistency (5 vs 4) — GPT-4o tied for 1st of 53, DeepSeek ranks 38 of 53. Ties: constrained_rewriting (3), safety_calibration (1), and agentic_planning (4) — both models performed identically on those tasks. Additionally, GPT-4o has external benchmark results to consider: on SWE-bench Verified (Epoch AI) it scores 31%, on MATH Level 5 (Epoch AI) 53.3%, and on AIME 2025 (Epoch AI) 6.4% (these are Epoch AI scores, not our internal 1–5 ratings). In practice this pattern means DeepSeek is the stronger choice for long-document tasks, structured JSON outputs, multilingual output, and strategic/creative reasoning at lower cost; GPT-4o is better for tool-driven workflows, classification routing, persona-heavy assistants, and when you need image/file inputs.

DeepSeek V3.1 Terminus costs $0.21 per mTok input + $0.79 per mTok output = $1.00 per mTok combined. GPT-4o costs $2.50 input + $10.00 output = $12.50 per mTok combined. Assuming a 50/50 input/output split, total cost for 1M tokens (1,000 mTok) is $1,000 on DeepSeek vs $12,500 on GPT-4o; for 10M tokens it's $10,000 vs $125,000; for 100M tokens it's $100,000 vs $1,250,000. The cost gap matters for any high-throughput product (chatting with many users, large-scale document processing, embedding/ingest pipelines) — teams with heavy token volumes or tight budgets should default to DeepSeek for lower unit cost, while teams that require GPT-4o’s multimodal inputs or better tool integration must budget for roughly 12.5x higher token costs.

Choose DeepSeek V3.1 Terminus if you need: long-context retrieval and summarization (score 5 vs 4, tied for 1st), robust structured output (5 vs 4, tied for 1st), multilingual parity (5 vs 4), strong strategic analysis (5 vs 2), and a vastly lower price per token. Choose GPT-4o if you need: reliable tool calling and function sequencing (tool_calling 4 vs 3, rank 18 vs 47), higher faithfulness and classification (faithfulness 4 vs 3; classification tied for 1st), persona consistency (5 vs 4), or multimodal inputs (text+image+file -> text). If you expect millions of tokens per month, cost favors DeepSeek; if a specific multimodal or tool-driven capability is required and budget is available, use GPT-4o.