GPT-5 Nano vs Grok Code Fast 1

Summary of test-by-test outcomes (our 12-test suite):

• Wins for GPT-5 Nano (modelA): structured output 5 vs 4 (tied for 1st of 54 with 24 others), strategic analysis 4 vs 3 (A ranks 27 of 54), long context 5 vs 4 (A tied for 1st of 55 with 36 others), safety calibration 4 vs 2 (A ranks 6 of 55), multilingual 5 vs 4 (A tied for 1st of 55 with 34 others). These wins translate to reliable JSON/schema outputs, superior 30k+ token retrieval behavior, stronger safety refusals/acceptances, and better non-English parity in our tests.
• Wins for Grok Code Fast 1 (modelB): classification 4 vs 3 (B tied for 1st of 53 with 29 others) and agentic planning 5 vs 4 (B tied for 1st of 54 with 14 others). That indicates Grok is stronger for routing/categorization tasks and goal decomposition/agentic workflows in our tests.
• Ties: constrained rewriting (3/3), creative problem solving (3/3), tool calling (4/4), faithfulness (4/4), persona consistency (4/4). For those tasks both models perform similarly in our suite.
• External math benchmarks (supplementary): GPT-5 Nano scores 95.2% on MATH Level 5 and 81.1% on AIME 2025 (Epoch AI) — evidence of strong competition-level math performance beyond our internal 1–5 tests. Grok Code Fast 1 has no external math scores in the payload to compare. Interpretation for real tasks: choose GPT-5 Nano when you need strict schema outputs, very long-context retrieval, multilingual parity, or stronger safety calibration. Choose Grok Code Fast 1 if classification fidelity and agentic planning (decomposition, recovery) are primary product requirements — but expect higher per-token costs.

Costs per 1,000 tokens (mTok): GPT-5 Nano input $0.05 / output $0.40; Grok Code Fast 1 input $0.20 / output $1.50. At scale (assuming 1,000 mTok = 1M tokens): per 1M tokens GPT-5 Nano = input $50, output $400, combined (1M in + 1M out) $450; Grok = input $200, output $1,500, combined $1,700. At 10M tokens (10k mTok) combined: GPT-5 Nano $4,500 vs Grok $17,000. At 100M tokens combined: GPT-5 Nano $45,000 vs Grok $170,000. In short, Grok costs ~3.78× more overall per token in typical input+output scenarios; teams with high-volume, cost-sensitive deployments should favor GPT-5 Nano, while teams willing to pay for Grok’s specific strengths (classification/agentic planning) can justify the premium for those use cases.

Choose GPT-5 Nano if you need cost-efficient production inference with top-tier structured-output (5/5), long-context (5/5), multilingual (5/5), and better safety (4/5) — plus strong external math scores (MATH Level 5 95.2%, AIME 2025 81.1% per Epoch AI). Choose Grok Code Fast 1 if your product relies on best-in-class classification (4/5, tied for 1st) or agentic planning (5/5, tied for 1st) and you can absorb ~3.8× higher per-token costs for input+output.