Question 1

What is GPT-5.1?

Accepted Answer

GPT-5.1 is a model from OpenAI, released on Nov 12, 2025. GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5. It uses adaptive reasoning to allocate computation dynamically, responding quickly to simple queries while spending more depth on complex tasks. The model produces clearer, more grounded explanations with reduced jargon, making it easier to follow even on technical or multi-step problems. Built for broad task coverage, GPT-5.1 delivers consistent gains across math, coding, and structured analysis workloads, with more coherent long-form answers and improved tool-use reliability. It also features refined conversational alignment, enabling warmer, more intuitive responses without compromising precision. GPT-5.1 serves as the primary full-capability successor to GPT-5.

Question 2

How much does GPT-5.1 cost?

Accepted Answer

On the Respan gateway, input starts at $1.25 per 1M tokens on every provider, and output starts at $10.00 per 1M tokens on every provider, after gateway discounts.

Question 3

Which providers serve GPT-5.1 on Respan?

Accepted Answer

5 providers serve GPT-5.1: Azure OpenAI, OpenAI, OpenRouter, and Perplexity. Azure OpenAI and Perplexity require your own provider API key (BYOK).

Question 4

What is GPT-5.1's context window?

Accepted Answer

GPT-5.1 accepts up to 400K tokens of context on its largest provider route.

Question 5

How do I use GPT-5.1 with the Respan gateway?

Accepted Answer

Point any OpenAI-compatible SDK at https://api.respan.ai/api/ with your Respan API key and set the model to "openai/gpt-5.1-2025-11-13". To set it up with a coding agent, copy the agent setup prompt at the top of this page.

Question 6

How fast is GPT-5.1?

Accepted Answer

Over the last 30 days of requests through the Respan gateway, the fastest provider was OpenAI at 80 tokens per second, and the lowest response latency was 0.7 seconds on OpenAI. Speed varies with request size and provider.

Question 7

Where does GPT-5.1 rank on the Respan Index?

Accepted Answer

GPT-5.1 scores 32.4 out of 100 on the Respan Index v1.1, ranking #62 of 138 models. By category: Coding 14.4, Agents 35.8, Reasoning 30.1, Knowledge & language 47.9, and Human preference 50.1. The Respan Index combines independent and lab-reported benchmark results into one score, using benchmark data collected by llmmetric.com.

Question 8

How does GPT-5.1 score on benchmarks?

Accepted Answer

GPT-5.1 has 16 published benchmark scores, including SWE-bench Verified 68%, Vending-Bench 2 1473.43, and GPQA Diamond 87.6%. Each score links to where it was published; the data is collected by llmmetric.com.

Provider	Context	Input	Output
Azure OpenAIBYOK only`azure/gpt-5.1`	400K	$1.25/M	$10.00/M
OpenAI`openai/gpt-5.1`	400K	$1.25/M	$10.00/M
OpenAI`openai/gpt-5.1-2025-11-13`	400K	$1.25/M	$10.00/M
OpenRouter`openrouter/openai/gpt-5.1`	400K	$1.25/M	$10.00/M
PerplexityBYOK only`perplexity/openai/gpt-5.1`	400K	$1.25/M	$10.00/M

GPT-5.1

Providers

Certified where it counts.

Pricing

Cost by volume

Throughput and latency

Output speed

Time to first token

Response latency

Benchmarks

Respan Indexv1.1

Coding3

Apps

GPT-5.1 FAQ

Works with your entire stack

Built for AI agents.
Break less.
Ship more.

Agents1

Reasoning4

Math2

Knowledge2

Arena3

Other1