Which is cheaper, GPT-4 Turbo or GPT-5.1 Codex Mini?
As of August 25, 2026, GPT-5.1 Codex Mini is 94% cheaper on blended LLM API pricing. GPT-5.1 Codex Mini costs $0.25 per million input tokens and $2.00 per million output tokens ($2.25 blended 1M-in + 1M-out). GPT-4 Turbo costs $10.00 / $30.00 per million tokens ($40.00 blended). Sources: https://developers.openai.com/api/docs/pricing 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 GPT-4 Turbo vs GPT-5.1 Codex Mini cost per million tokens?
GPT-4 Turbo OpenAI API pricing is $10.00 input and $30.00 output per million tokens via OpenAI. GPT-5.1 Codex Mini OpenAI API pricing is $0.25 input and $2.00 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, GPT-4 Turbo or GPT-5.1 Codex Mini?
GPT-4 Turbo has a published HumanEval score of 87.1%. GPT-5.1 Codex Mini does not have that eval on this page yet.
What is the context window for GPT-4 Turbo vs GPT-5.1 Codex Mini?
GPT-4 Turbo supports a 128K token context window, while GPT-5.1 Codex Mini supports 400K tokens. GPT-5.1 Codex Mini 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, GPT-4 Turbo or GPT-5.1 Codex Mini?
GPT-5.1 Codex Mini leads on 1 of 1 shared benchmarks versus GPT-4 Turbo'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 GPT-4 Turbo or GPT-5.1 Codex Mini better for production use?
Both GPT-4 Turbo and GPT-5.1 Codex Mini are production API models. For cost-sensitive production traffic, GPT-5.1 Codex Mini 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 GPT-4 Turbo and GPT-5.1 Codex Mini in my app?
Yes. Call GPT-4 Turbo through OpenAI and GPT-5.1 Codex Mini 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 GPT-4 Turbo vs GPT-5.1 Codex Mini pricing data?
List rates are the latest published OpenAI API pricing and OpenAI API pricing, quoted per million tokens. Official rate sheets: https://developers.openai.com/api/docs/pricing 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 GPT-4 Turbo and GPT-5.1 Codex Mini?
GPT-4 Turbo supports up to 4K output tokens per request, while GPT-5.1 Codex Mini 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, GPT-4 Turbo or GPT-5.1 Codex Mini?
GPT-4 Turbo runs at approximately 100 tokens/second while GPT-5.1 Codex Mini runs at 200 tokens/second. GPT-5.1 Codex Mini is faster in raw throughput. 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 GPT-4 Turbo vs GPT-5.1 Codex Mini comparison?
Use the model pickers at the top of this LLM comparison. Search any model in the index and the URL updates. Open GPT-4 Turbo or GPT-5.1 Codex Mini from the sidebar for the single-model API pricing page, or go back to the LLM pricing table to sort by cheapest blended cost.
