GPT-5.1 vs Grok 3
For general-purpose, multimodal, and cost-sensitive production use, GPT-5.1 is the pragmatic pick — it matches or outperforms Grok 3 on several creative and constrained tasks while costing less. Grok 3 wins where strict schema adherence and agentic planning matter (structured output 5, agentic planning 5), but it comes at a higher per-token price.
openai
GPT-5.1
Benchmark Scores
External Benchmarks
Pricing
Input
$1.25/MTok
Output
$10.00/MTok
modelpicker.net
xai
Grok 3
Benchmark Scores
External Benchmarks
Pricing
Input
$3.00/MTok
Output
$15.00/MTok
modelpicker.net
Benchmark Analysis
Head-to-head across our 12-test suite: • Wins for GPT-5.1: constrained rewriting (GPT-5.1 4 vs Grok 3 3). GPT-5.1 ranks 6 of 53 on constrained rewriting, indicating better performance compressing or fitting hard limits. creative problem solving (GPT-5.1 4 vs Grok 3 3) — GPT-5.1 ranks 9 of 54, so it generates more novel, feasible ideas in our tests. • Wins for Grok 3: structured output (Grok 3 5 vs GPT-5.1 4) — Grok is tied for 1st on structured output (tied with 24 others), so it is more reliable for JSON schema compliance and format adherence. agentic planning (Grok 3 5 vs GPT-5.1 4) — Grok 3 is tied for 1st, making it stronger at decomposition and recovery planning. • Ties (equal scores): strategic analysis (5/5), tool calling (4/4), faithfulness (5/5), classification (4/4), long context (5/5), safety calibration (2/2), persona consistency (5/5), multilingual (5/5). Notably, GPT-5.1 posts external benchmark results: 68 on SWE-bench Verified and 88.6 on AIME 2025 (scores reported by Epoch AI), which supports its coding/math competence on third-party tests. Practical takeaway: choose Grok 3 when strict schema compliance and top-tier agentic planning are gating requirements; choose GPT-5.1 when you need multimodal context, stronger constrained rewriting and creative problem solving, or a lower-cost option with corroborating external math/coding scores.
Pricing Analysis
Pricing per 1,000 tokens: GPT-5.1 costs $1.25 input + $10 output; Grok 3 costs $3 input + $15 output. Assuming a 50/50 input/output split, monthly costs are: • 1M tokens — GPT-5.1: $5,625; Grok 3: $9,000 (Grok +$3,375). • 10M tokens — GPT-5.1: $56,250; Grok 3: $90,000 (Grok +$33,750). • 100M tokens — GPT-5.1: $562,500; Grok 3: $900,000 (Grok +$337,500). At scale, the difference is material for high-volume chat, summarization, or generation products; teams with tight cost budgets or heavy output token usage will prefer GPT-5.1. Enterprises that require Grok 3’s stronger structured-output and agentic planning may justify the premium.
Real-World Cost Comparison
Bottom Line
Choose GPT-5.1 if you need multimodal input (text+image+file->text), a very large 400,000-token context window, better constrained rewriting and creative problem solving, or lower token costs (input $1.25/mTok, output $10/mTok). Choose Grok 3 if your product requires rock-solid structured outputs (structured output 5) or top-ranked agentic planning and you're willing to pay the premium (input $3/mTok, output $15/mTok). If you care about external verification for coding/math, GPT-5.1 has SWE-bench Verified 68 and AIME 2025 88.6 (Epoch AI); if schema fidelity and enterprise extraction are core, pick Grok 3.
How We Test
We test every model against our 12-benchmark suite covering tool calling, agentic planning, creative problem solving, safety calibration, and more. Each test is scored 1–5 by an LLM judge. Read our full methodology.