GPT-5.1 Chat vs Gemini 3 Pro
Benchmarks, API Token Pricing, Context Window & Speed Comparison
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GPT-5.1 Chat by OpenAI and Gemini 3 Pro by Google represent two of the frontier AI models analyzed in our comprehensive 2026 AI benchmark and LLM comparison. In this head-to-head evaluation, we examine API token pricing, context window specifications, inference speed (tokens per second), and empirical reasoning performance. From a pure economic perspective, GPT-5.1 Chat holds a notable pricing advantage for token ingestion. On output generation, GPT-5.1 Chat is more economical per million generated tokens. In data-heavy architectures requiring extensive repository or document analysis, Gemini 3 Pro provides an expanded memory horizon with 2,000K tokens. In latency-sensitive production environments, GPT-5.1 Chat leads in tokens-per-second throughput, making it ideal for real-time conversational agents and high-concurrency workflows. Below is the complete empirical head-to-head breakdown across cost, speed, context, and capability matrices.
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GPT-5.1 Chat
Conversational 5.1A chat-tuned GPT-5.1 for refined assistance, writing and product conversation.
$0.00 / 1M
$0.00 / 1M
128K tokens
74%
Gemini 3 Pro
Context KingGoogle's context king with an industry-leading 2M-token window and the #1 LMSYS Arena ranking, purpose-built for long-document and multimodal reasoning.
$2.00 / 1M
$12.00 / 1M
2M tokens
76.2%
Key Differences at a Glance
- GPT-5.1 Chat is 1.0x cheaper for API usage (input + output tokens combined).
- Gemini 3 Pro has a larger context window (2M vs 128K tokens).
- GPT-5.1 Chat is faster at 132 tok/s vs 118 tok/s.
- Gemini 3 Pro leads on SWE-bench coding (76.2% vs 74.0%).
| Feature | GPT-5.1 Chat | Gemini 3 Pro |
|---|---|---|
Intelligence Index Composite reasoning & knowledge score (0-100) | 60 | 62 |
Provider | OpenAI | |
Input Price Cost per million input tokens | $0.00 / 1M | $2.00 / 1M |
Output Price Cost per million output tokens | $0.00 / 1M | $12.00 / 1M |
Blended Price Weighted 7:2:1 cache:input:output per 1M | $0.00 / 1M | $1.74 / 1M |
Context Window Maximum input + output tokens | 128K tokens~192 A4 pages of text | 2M tokens~3,000 A4 pages of text |
Max Output Tokens Per single request | 16K | 66K |
Throughput Speed Tokens generated per second | 132 tok/s | 118 tok/s |
SWE-bench Verified Real-world software engineering | 74% | 76.2% |
GPQA Diamond Graduate-level reasoning | 71.8% | 73.5% |
Cached Input Price Prompt caching discount per 1M tokens | $0.00 / 1M | $0.20 / 1M |
Who Wins Where?
At-a-glance decision frameworkEmpirical Head-to-Head Benchmark Scores
Official evaluation metrics verified by independent third-party research labs.
Industry benchmark evaluating real-world GitHub issue resolution and multi-file debugging.
Challenging questions created by domain experts to test complex PhD-level reasoning.
Hardened reasoning and academic knowledge benchmark with reduced lucky-guess probability.
Crowdsourced human preference evaluation based on blind, head-to-head model battles.
Extremely difficult, closed-ended questions spanning the frontier of human expert knowledge.
Autonomous multi-step tasks executed inside a real command-line terminal environment.
Research-grade coding problems drawn from real scientific and numerical workloads.
Contamination-free competitive programming problems collected continuously over time.
American Invitational Mathematics Examination — multi-step Olympiad-level reasoning.
Accuracy when reasoning over very large inputs that fill the model context window.
Tokens emitted per second during active generation streaming.
Latency & Response Time
Time to first token (TTFT) and estimated end-to-end response time for a typical 500-token response.
Real-Time Interactive Token Cost Simulator
Adjust sliders to calculate projected monthly cloud API spending with prompt caching discounts.
GPT-5.1 Chat · Strengths & Key Advantages
- Improved conversational quality over GPT-5 Chat
- Well tuned for writing and product workflows
- Strong at multi-turn editing of long documents
Considerations & Trade-offs
- No standalone API pricing — subscription access only
- Smaller context window than the API tier
Gemini 3 Pro · Strengths & Key Advantages
- Industry-leading 2M-token context window (10x most rivals)
- #1 LMSYS Chatbot Arena ranking at launch
- Native multimodal input across text, image, audio, and video
- 90% cached-context discount for repeated long inputs
Considerations & Trade-offs
- Higher rates apply above the 200K standard tier
- Output price ($12/1M) above GPT-5.1 for short tasks
Token Use & Task Economics
Estimated cost and token consumption to complete one representative agentic task.
| Metric | GPT-5.1 Chat | Gemini 3 Pro |
|---|---|---|
Cost per Task Estimated USD to finish one task | $1.48 | $2.40 |
Output Tokens / Task Tokens generated per task | 52K | 60K |
Reasoning Tokens / Task Thinking tokens burned per task | 28K | 31K |
Technical Specifications
Architecture, release timeline, capabilities, and modalities.
| Feature | GPT-5.1 Chat | Gemini 3 Pro |
|---|---|---|
| Official API Model ID (SDK) | gpt-5-1-chat | models/gemini-3-pro |
| API Protocol | OpenAI Responses API & Chat Completions v1 | Google Gemini API (generateContent) + OpenAI-Compatible SDK |
| Release Date | 2025-11 | 2025-11 |
| Knowledge Cutoff | October 2024 | January 2025 |
| Architecture | Chat-tuned unified reasoning model | Sparse Multimodal MoE |
| Parameters | Confidential | Confidential |
| Enterprise Rate Limits (RPM / TPM) | 10,000 – 30,000 RPM (Tier 5 Enterprise) · 800,000 – 2,000,000 TPM | 10,000 – 30,000 RPM (Tier 5 Enterprise) · 4,000,000 – 10,000,000 TPM |
| Long-Context Tier (>128K/200K) | Free across full context window (only KV-cache VRAM scales) | Standard rate up to 200K tokens; 2x input/output tier above 200K tokens |
| Prompt Cache Policy & TTL | Automatic prefix KV-caching in vLLM / SGLang (0 cost) | Implicit + Explicit Context Caching at $0.2/1M with configurable TTL |
| Computer Use / GUI Agent | Supported (Screen coordinate grounding, browser & desktop GUI action loops) | Supported (Screen coordinate grounding, browser & desktop GUI action loops) |
| MCP & Parallel Tool Calling | Native MCP Client/Server ready · Parallel function calling | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema |
| Web Search Grounding & Sandbox | Native Web Search tool + Hosted Code Interpreter & File Search RAG | Built-in Google Search Grounding + Managed Python Code Execution Sandbox |
| Official Fine-Tuning Support | Supervised Fine-Tuning (SFT), Direct Preference (DPO) & Reinforcement Fine-Tuning (RFT) | Vertex AI Supervised Adapter Tuning & Context Distillation |
| Multimodal Token Billing | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) · Audio (~25–32 tokens/sec) · Video (~258–300 tokens/sec) |
| Quantization & Min GPU VRAM | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) |
| Safety & Frontier Classification | OpenAI Preparedness Framework Audited & System Card Published | Google DeepMind Frontier Safety Framework Verified |
| Enterprise Compliance (ZDR/HIPAA/SOC2) | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier |
| Input Modalities | text, vision | text, vision, audio, video |
| Output Modalities | text | text |
GPT-5.1 Chat vs Gemini 3 Pro: Quick Answers
Which is more intelligent, GPT-5.1 Chat or Gemini 3 Pro?
Gemini 3 Pro is more intelligent. It scores 62 compared with 60 on the composite Intelligence Index.
Which model is faster?
GPT-5.1 Chat is faster, generating 132 tokens per second compared with 118 tokens per second.
Which model is cheaper to run?
GPT-5.1 Chat is cheaper at $0.00 per 1M tokens blended, compared with $1.74 (7:2:1 cache:input:output ratio).
Which model has lower latency?
GPT-5.1 Chat has lower latency, with a time to first token of 1.18s compared with 1.80s.
Which model has a larger context window?
Gemini 3 Pro has a larger context window, supporting 2M tokens compared with 128K tokens.
Verdict
Verdict & Model Selection Recommendation: Choose GPT-5.1 Chat if your priority is Interactive ChatGPT experiences. Its performance in demanding tasks justifies its operational token cost. Choose Gemini 3 Pro if your workflow prioritizes Long-document analysis, full-codebase reasoning, and multimodal tasks needing 500K+ tokens. For large-scale batch processing or customer-facing conversational interfaces, its balance of speed and economics delivers superior ROI.
Frequently asked questions
How does GPT-5.1 Chat compare to Gemini 3 Pro in API token pricing and cost per token?+
GPT-5.1 Chat costs $0.00 per 1M input tokens and $0.00 per 1M output tokens, whereas Gemini 3 Pro costs $2.00 input and $12.00 output. Overall, GPT-5.1 Chat is the more cost-effective model for high-volume API pipelines. Both models support prompt caching discounts of up to 90% for repeated prompt prefixes.
Which model has a larger context window: GPT-5.1 Chat or Gemini 3 Pro?+
GPT-5.1 Chat supports a context window of 128K tokens (~96k words), while Gemini 3 Pro supports 2,000K tokens (~1,500k words). Therefore, Gemini 3 Pro can process more textual data and document context in a single prompt.
Which AI model is better for software engineering and coding: GPT-5.1 Chat or Gemini 3 Pro?+
GPT-5.1 Chat scores 74% on SWE-bench Verified while Gemini 3 Pro scores 76.2%. For autonomous software engineering and multi-file debugging, Gemini 3 Pro holds the verified benchmark lead.
What is the difference in reasoning capability and extended thinking between GPT-5.1 Chat and Gemini 3 Pro?+
GPT-5.1 Chat features native chain-of-thought extended thinking mode with configurable reasoning effort. In contrast, Gemini 3 Pro provides chain-of-thought reasoning depth for complex math and science.
How does inference speed (tokens per second) compare between GPT-5.1 Chat and Gemini 3 Pro?+
GPT-5.1 Chat generates approximately 132 tokens per second, while Gemini 3 Pro delivers 118 tokens per second. In latency-sensitive production environments, GPT-5.1 Chat provides faster time-to-first-token (TTFT) and higher streaming response velocity.
Can you implement a tiered LLM routing setup combining GPT-5.1 Chat and Gemini 3 Pro to optimize costs?+
Yes! High-efficiency architectures route high-frequency routine classification and conversational tasks to GPT-5.1 Chat to save operational costs, and dynamically escalate complex architectural queries or reasoning tasks to Gemini 3 Pro. This tiered routing pattern cuts overall API bills by up to 70%.
Understand key metrics like context window, token pricing, reasoning mode, and SWE-bench scores in our comprehensive AI glossary.
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Benchmark scores, token prices, and rate limits evolve rapidly as AI labs release model updates. Always verify current specifications and pricing on the official provider documentation.
Sources: GetInfoUs Independent AI Benchmarks & Official API Specs