Which is cheaper, Composer 2 Fast or GPT-5.1 Codex?
As of August 20, 2026, Composer 2 Fast is 20% cheaper on blended LLM API pricing. Composer 2 Fast costs $1.50 per million input tokens and $7.50 per million output tokens ($9.00 blended 1M-in + 1M-out). GPT-5.1 Codex costs $1.25 / $10.00 per million tokens ($11.25 blended). Sources: https://cursor.com/docs/models/cursor-composer-2 and https://developers.openai.com/api/docs/pricing. The cheapest LLM for your app still depends on how many output tokens you generate.
How much does Composer 2 Fast vs GPT-5.1 Codex cost per million tokens?
Composer 2 Fast Cursor API pricing is $1.50 input and $7.50 output per million tokens via Cursor. GPT-5.1 Codex OpenAI API pricing is $1.25 input and $10.00 output per million tokens via OpenAI. Use those four numbers, not ChatGPT Plus or Claude Pro subscription prices, when you are comparing APIs.
Which is better for coding, Composer 2 Fast or GPT-5.1 Codex?
GPT-5.1 Codex has a published SWE-bench Verified score of 73.7%. Composer 2 Fast does not have that eval on this page yet.
What is the context window for Composer 2 Fast vs GPT-5.1 Codex?
Composer 2 Fast supports a 200K token context window, while GPT-5.1 Codex supports 400K tokens. GPT-5.1 Codex offers a larger context window. Filling a larger window bills more input tokens, so the cheaper-per-million model can still cost more on long documents.
Which model performs better on benchmarks, Composer 2 Fast or GPT-5.1 Codex?
Composer 2 Fast leads on 1 of 1 shared benchmarks versus GPT-5.1 Codex's 0 wins. Check the comparison table for GPQA Diamond, SWE-bench, MMLU, HLE, and the other evals we track. Token price and benchmark score together are the usual LLM comparison, not either number alone.
Is Composer 2 Fast or GPT-5.1 Codex better for production use?
Both Composer 2 Fast and GPT-5.1 Codex are production API models. For cost-sensitive production traffic, Composer 2 Fast has better economics on the blended 1M-in + 1M-out scale. For maximum capability, weight the benchmark table for your domain. Many production stacks route cheap models for drafts and a frontier model for the hard turn, which is usually cheaper than sending everything to the expensive API.
Can I switch between Composer 2 Fast and GPT-5.1 Codex in my app?
Yes. Call Composer 2 Fast through Cursor and GPT-5.1 Codex through OpenAI with separate API keys, or through a gateway that already wraps both. Keep prompts in tokens, not characters, when you estimate the invoice. AnotherWrapper templates can swap providers without rewriting auth and billing.
How accurate is this Composer 2 Fast vs GPT-5.1 Codex pricing data?
List rates are the latest published Cursor API pricing and OpenAI API pricing, quoted per million tokens. Official rate sheets: https://cursor.com/docs/models/cursor-composer-2 and https://developers.openai.com/api/docs/pricing. Prompt caching, batch APIs, and committed-use discounts can change the invoice. Benchmark scores are from official publications and independent evals, updated as new numbers land.
What is the output token limit for Composer 2 Fast and GPT-5.1 Codex?
Composer 2 Fast supports up to an unspecified number of output tokens per request, while GPT-5.1 Codex supports up to 128K output tokens. Output tokens are usually the expensive half of API pricing, so a higher max output cap is a capability, not a discount.
Which model has better throughput, Composer 2 Fast or GPT-5.1 Codex?
GPT-5.1 Codex has a measured throughput of approximately 50 tokens/second. Throughput data for Composer 2 Fast is not yet available. Throughput (tokens per second) and time-to-first-token are why two models with the same per-million-token price can still feel different in chat and agents.
How do I switch the models in this Composer 2 Fast vs GPT-5.1 Codex comparison?
Use the model pickers at the top of this LLM comparison. Search any model in the index and the URL updates. Open Composer 2 Fast or GPT-5.1 Codex from the sidebar for the single-model API pricing page, or go back to the LLM pricing table to sort by cheapest blended cost.
