GPT-5.1 Codex API pricing
Standard tier, blended at 3:1 input to output: $3.44 per million tokens.
OpenRouter charges $1.25 per million input tokens and $10.00 per million output tokens for GPT-5.1 Codex. It is sold in 2 forms, from $3.44 to $3.44 blended; the table below shows what each costs against standard. 2 of the models nearest it in price are cheaper on a blended basis.
Every tier of GPT-5.1 Codex
Blended at 3:1 input to output. The last column compares each against the standard tier.
| Source | ||||||||
|---|---|---|---|---|---|---|---|---|
| Standard Standard | gpt-5.1-codex | OpenRouter | $1.25 | $10.00 | $0.130 | $3.44 | Standard | ↗ |
| Max | gpt-5.1-codex-max | OpenRouter | $1.25 | $10.00 | $0.125 | $3.44 | Same | ↗ |
Prices last checked: . Methodology
Which tier to use
What each costs against standard in our data, and the job it is for.
Max variant
The vendor also lists a max variant of gpt-5.1-codex, listed at the same price as standard. It is the same model tuned or wired for one job, so pick one only when that is your job; otherwise standard is the reference price.
Against the models nearest in price
Standard tiers, blended at a 3:1 input to output ratio.
| Source | ||||||
|---|---|---|---|---|---|---|
| GPT-5.1 Codex This model | OpenRouter | $1.25 | $10.00 | 400,000 | $3.44 | ↗ |
| GPT-5.1 | OpenAI | $1.25 | $10.00 | 272,000 | $3.44 | ↗ |
| GPT-5 | OpenAI | $1.25 | $10.00 | 272,000 | $3.44 | ↗ |
| Gemini 2.5 Pro | Google AI | $1.25 | $10.00 | 1,048,576 | $3.44 | ↗ |
| GPT-4.1 | OpenAI | $2.00 | $8.00 | 1,047,576 | $3.50 | ↗ |
| o3 | OpenAI | $2.00 | $8.00 | 200,000 | $3.50 | ↗ |
| Llama 3.1 405B Instruct | Together AI | $3.50 | $3.50 | 4,096 | $3.50 | ↗ |
| Mistral Large | OpenRouter | $2.00 | $6.00 | 128,000 | $3.00 | ↗ |
| Grok 4.5 | xAI | $2.00 | $6.00 | 500,000 | $3.00 | ↗ |
Prices last checked: . Methodology
Questions
How much does GPT-5.1 Codex cost per million tokens?
$1.25 per million input tokens and $10.00 per million output tokens, with cached input at $0.130. At a 3:1 input to output mix that blends to $3.44. Checked 28 Oct 2026.
What would GPT-5.1 Codex cost for a real workload?
A thousand requests a day at 2,000 input and 600 output tokens each comes to $255.00 a month on the standard tier.
What is the context window for GPT-5.1 Codex?
400,000 tokens of input, with up to 128,000 tokens of output.
GPT-5.1 · GPT-5 · Gemini 2.5 Pro · GPT-4.1 · o3 · All OpenRouter models · Cost calculator