DeepSeek V3.1 Terminus vs Grok 4.20

Across our 12-test suite (scores shown as our 1–5 internal scale): Grok 4.20 wins five tests outright and ties seven. Wins (Grok > DeepSeek): constrained rewriting 4 vs 3 — Grok ranks 6 of 53 (good for tight compression and character-limited transformations); tool calling 5 vs 3 — Grok is tied for 1st of 54 on tool calling (critical for accurate function selection and argument sequencing), while DeepSeek ranks 47 of 54; faithfulness 5 vs 3 — Grok is tied for 1st of 55 (low hallucination, sticks to source), DeepSeek ranks 52 of 55 (weak on faithfulness in our testing); classification 4 vs 3 — Grok tied for 1st of 53 (better routing and categorization); persona consistency 5 vs 4 — Grok tied for 1st of 53 (resists injection and maintains character better). Ties (both models score the same): structured output 5/5 (both tied for 1st — reliable JSON/schema output), strategic analysis 5/5 (both tied for 1st — nuanced tradeoff reasoning), creative problem solving 4/4 (both rank 9 of 54), long context 5/5 (both tied for 1st — robust 30k+ retrieval), safety calibration 1/1 (both poor at safety calibration in our tests), agentic planning 4/4 (both rank 16 of 54), multilingual 5/5 (both tied for 1st). Notable gaps: DeepSeek is competitive on long context (5) and structured output (5) where it ranks tied for 1st, so tasks needing huge context windows or strict schema adherence can use DeepSeek to save cost without losing quality. Conversely, Grok’s clear advantages on tool calling (5 vs 3) and faithfulness (5 vs 3) make it preferable for production agents, tool-integrated assistants, and systems where hallucination risk is unacceptable.

List prices from the payload: DeepSeek V3.1 Terminus charges $0.21 input / $0.79 output per mTok; Grok 4.20 charges $2 input / $6 output per mTok. Using a simple 50/50 input/output token split (explicit assumption), per-month cost examples: 1M tokens = 1,000 mTok -> DeepSeek ≈ $500; Grok ≈ $4,000. Scale: 10M tokens → DeepSeek ≈ $5,000 vs Grok ≈ $40,000. 100M tokens → DeepSeek ≈ $50,000 vs Grok ≈ $400,000. The payload's priceRatio (0.1316667) reflects that DeepSeek's listed per-mTok rates are ~13.17% of Grok's listed per-mTok rates. Who should care: startups, high-volume API customers, and large-scale fine-tuning/proofing pipelines will see materially different monthly bills; teams prioritizing production-grade tool calling, faithfulness, and classification should budget for Grok's 4–8x (input) and 7.6–12.5x (combined) higher costs depending on usage patterns.

Choose DeepSeek V3.1 Terminus if: you need massive-context processing and strict structured outputs at low cost — it scores 5 on long context and structured output and its listed rates ($0.21/$0.79 per mTok) make it ~13% of Grok's price. Choose Grok 4.20 if: you need reliable tool calling, low-hallucination outputs, strong classification and persona consistency — Grok scores 5 on tool calling and faithfulness, and ranks tied for 1st in those categories despite higher listed rates ($2/$6 per mTok). If you must balance both, run Grok where agentic tool reliability and faithfulness matter and run DeepSeek for high-volume context-heavy or schema-bound workloads to control costs.