R1 0528 vs GPT-5.1

Head-to-head summary from our tests: R1 0528 wins tool_calling (R1 score 5 vs GPT-5.1 score 4) and ranks tied for 1st for tool_calling among 54 models (tied with 16 others). R1 also wins agentic_planning (5 vs 4) and is tied for 1st in that category (tied with 14 others). On safety_calibration R1 scores 4 vs GPT-5.1's 2; R1 ranks 6 of 55 (4 models share that score) while GPT-5.1 ranks 12 of 55. GPT-5.1 wins strategic_analysis (5 vs R1's 4) and is tied for 1st in strategic_analysis (tied with 25 others); R1 is ranked 27 of 54 there. Many benchmarks are ties: faithfulness (both 5, tied for 1st), classification (both 4, tied for 1st), long_context (both 5, tied for 1st), persona_consistency (both 5, tied for 1st), multilingual (both 5, tied for 1st), constrained_rewriting (both 4, rank 6), creative_problem_solving (both 4, rank 9), and structured_output (both 4, rank 26). External benchmarks (Epoch AI): R1 scores 96.6% on MATH Level 5 (math_level_5, Epoch AI) and places rank 5 of 14 for that test; GPT-5.1 posts 88.6% on AIME 2025 (aime_2025, Epoch AI) vs R1's 66.4% on the same AIME test, putting GPT-5.1 at rank 7 of 23 and R1 at rank 16 of 23. GPT-5.1 also has a 68% on SWE-bench Verified (Epoch AI) and ranks 7 of 12 there; R1 has no SWE-bench score in the payload. What this means in practice: choose R1 when you need reliable function selection, tool sequencing, agentic planning, stronger safety calibration, long-context handling within its 163,840-token window, and much lower cost. Choose GPT-5.1 when you need the highest-tier strategic analysis, the largest context ceiling (400,000 tokens), or specific external-benchmark strengths on AIME and SWE-bench as reported by Epoch AI.

R1 0528 is materially cheaper. Per the payload, R1 input costs $0.50 per mtoken and output $2.15 per mtoken; GPT-5.1 charges $1.25 input and $10.00 output. Using a 50/50 input/output token split as a practical example: at 1M tokens/month R1 costs $1,325 vs GPT-5.1 $5,625; at 10M tokens/month R1 costs $13,250 vs GPT-5.1 $56,250; at 100M tokens/month R1 costs $132,500 vs GPT-5.1 $562,500. If your app is output-heavy (large generations), the output rate dominates: for 1M output tokens R1 = $2,150 vs GPT-5.1 = $10,000. The payload's priceRatio (0.215) summarizes this: R1 runs at ~21.5% of GPT-5.1's price for comparable token mixes. High-volume SaaS, startups, and cost-sensitive production deployments should prioritize R1 for the same baseline capabilities; teams that need GPT-5.1's specific strengths should budget for 4–5x higher monthly spend in common scenarios and up to ~5x or more on output-heavy workloads.

Choose R1 0528 if you need cost-efficient production deployments, robust tool calling and agentic workflows, strong safety calibration, and long-context performance at 163,840 tokens (good for high-throughput chat, automation, and multilingual/consistent persona use). Choose GPT-5.1 if your priority is state-level strategic analysis, the largest context window (400,000 tokens), multimodal inputs (text+image+file→text in the payload), or stronger AIME / SWE-bench results per Epoch AI — and you can absorb ~4–5x higher monthly API costs for similar token volumes.