GPT-5 Nano vs Grok 3

Overview: In our 12-test comparison Grok 3 wins five tests, GPT-5 Nano wins safety calibration, and six tests tie. Detailed walk-through: • Safety calibration: GPT-5 Nano 4 vs Grok 3 2 — Nano wins; Nano ranks 6 of 55 (tied with 3) vs Grok 3 rank 12 of 55. This means Nano better refuses harmful requests while allowing legitimate ones in our tests. • Classification: Grok 3 4 vs Nano 3 — Grok 3 tied for 1st (tied with 29 others out of 53) while Nano sits at rank 31 of 53; expect Grok 3 to route and tag text more accurately. • Faithfulness: Grok 3 5 vs Nano 4 — Grok 3 tied for 1st (32 models) vs Nano rank 34 of 55; Grok 3 sticks to source material more reliably in our benchmarks. • Strategic analysis: Grok 3 5 vs Nano 4 — Grok 3 tied for 1st (25 other models) vs Nano rank 27 of 54; Grok 3 performed better on nuanced tradeoffs and numeric reasoning. • Persona consistency: Grok 3 5 vs Nano 4 — Grok 3 tied for 1st (36 models) vs Nano rank 38 of 53; Grok 3 maintained character and resisted prompt injection more consistently. • Agentic planning: Grok 3 5 vs Nano 4 — Grok 3 tied for 1st vs Nano rank 16 of 54; Grok 3 better decomposed goals and recovered from failures. • Ties (no clear winner in our tests): structured output (both 5; both tied for 1st), tool calling (both 4; both rank 18 of 54), constrained rewriting (both 3), creative problem solving (both 3), long context (both 5; both tied for 1st), multilingual (both 5; both tied for 1st). Practical meaning: Grok 3 is the safer pick when you need routing, faithful summaries, agentic planning, or persona-driven assistants. GPT-5 Nano retains advantages in safety calibration and offers identical top-tier performance on long-context, structured output, and multilingual tasks, plus strong MATH-level scores: GPT-5 Nano scores 95.2% on MATH Level 5 and 81.1% on AIME 2025 (Epoch AI), which we list as supplementary external benchmarks.

We compare per-million-token input+output pricing (input_cost_per_mtok + output_cost_per_mtok). GPT-5 Nano: $0.05 + $0.40 = $0.45 per 1M tokens. Grok 3: $3 + $15 = $18.00 per 1M tokens. Monthly costs for combined input+output traffic: • 1M tokens: GPT-5 Nano $0.45 vs Grok 3 $18.00. • 10M tokens: GPT-5 Nano $4.50 vs Grok 3 $180.00. • 100M tokens: GPT-5 Nano $45.00 vs Grok 3 $1,800.00. At these volumes the price gap is material: at 100M tokens you pay an extra $1,755/month for Grok 3. Teams with heavy real-time chat, large-scale inference, or narrow-budget production workloads should care most; organizations prioritizing classification accuracy, faithful outputs, and agentic planning should budget for Grok 3 despite the higher cost.

Choose GPT-5 Nano if: • You need the lowest possible inference cost (about $0.45 per 1M input+output tokens). • You serve massive traffic (10M–100M tokens/month) or require ultra-low latency and very large context windows (400k tokens). • You prioritize safety calibration and long-context retrieval at scale. Choose Grok 3 if: • You need stronger classification, faithfulness, strategic analysis, persona consistency, or agentic planning (Grok 3 wins these five tests in our suite). • You’re building enterprise routing, extraction, or decisioning systems and can absorb higher runtime costs (about $18 per 1M tokens). • Accuracy and plan-based reasoning justify the higher bill.