DeepSeek V3.1 vs GPT-4.1

Overview (our 12-test suite): GPT-4.1 wins 5 tests, DeepSeek V3.1 wins 2, and 5 tests tie. Detailed test-by-test: - Tool calling: GPT-4.1 scores 5 vs DeepSeek 3; GPT-4.1 ranks "tied for 1st with 16 other models out of 54" while DeepSeek ranks 47 of 54. This means GPT-4.1 is markedly more reliable at selecting functions, producing correct arguments, and sequencing calls. - Constrained rewriting: GPT-4.1 5 vs DeepSeek 3; GPT-4.1 is "tied for 1st" (rank 1 of 53), so for tight character-limit compression GPT-4.1 is superior. - Strategic analysis: GPT-4.1 5 vs DeepSeek 4; GPT-4.1 ties for 1st (rank 1 of 54), making it the stronger choice for nuanced tradeoff reasoning with numbers. - Classification: GPT-4.1 4 vs DeepSeek 3; GPT-4.1 is "tied for 1st" (rank 1 of 53) so routing and labeling tasks favor GPT-4.1. - Multilingual: GPT-4.1 5 vs DeepSeek 4; GPT-4.1 is "tied for 1st" (rank 1 of 55), indicating more consistent non‑English parity. - Structured output: DeepSeek 5 vs GPT-4.1 4; DeepSeek is "tied for 1st" (rank 1 of 54) — expect better JSON/schema compliance and format adherence from DeepSeek. - Creative problem solving: DeepSeek 5 vs GPT-4.1 3; DeepSeek ties for 1st (rank 1 of 54) on delivering non-obvious, feasible ideas. - Faithfulness, Long context, Persona consistency, Safety calibration, Agentic planning: ties (faithfulness 5, long_context 5, persona_consistency 5, safety_calibration both 1, agentic_planning both 4). Rankings show both models tie at top in several dimensions (e.g., faithfulness and long-context). External benchmarks (Epoch AI): GPT-4.1 scores 48.5% on SWE-bench Verified, 83% on MATH Level 5, and 38.3% on AIME 2025; these external results (attributed to Epoch AI) supplement our internal wins and show GPT-4.1's competence on third‑party coding/math tasks. DeepSeek has no external scores in the payload; our internal tests show it excels at structured outputs and ideation while GPT-4.1 dominates tooling, constrained rewriting, strategic reasoning and multilingual performance.

Per the payload prices, DeepSeek V3.1 charges $0.15 input + $0.75 output = $0.90 per mTok; GPT-4.1 charges $2 input + $8 output = $10.00 per mTok. At 1M tokens/month (1,000 mTok): DeepSeek ≈ $900/month vs GPT-4.1 ≈ $10,000/month. At 10M tokens: $9,000 vs $100,000. At 100M tokens: $90,000 vs $1,000,000. DeepSeek runs at ~9.375% of GPT-4.1's per-token bill (priceRatio 0.09375). High-volume APIs, startups on tight margins, or applications where structured output quality matters should favor DeepSeek for cost savings; teams needing best-in-class tool calling, constrained rewriting, or multilingual accuracy should budget for GPT-4.1.

Choose DeepSeek V3.1 if you need rock-solid structured outputs (JSON/schema) or creative ideation at very high volume and want to cut costs dramatically — it costs $0.90/mTok vs GPT-4.1 $10.00/mTok. Choose GPT-4.1 if your product depends on reliable tool calling, constrained-rewrite fidelity, nuanced strategic analysis, high-quality classification, or top-tier multilingual behavior; budget for ~11x higher per-token spend and consider its external SWE-bench and math results (Epoch AI).