GPT 5.1 Codex API pricing
Azure OpenAI · chat model · 272K context · ranked #1355 of 1809 by input price
What GPT 5.1 Codex costs in practice
GPT 5.1 Codex is priced at $1.38 per million input tokens and $11 per million output tokens , with cached input billed at $0.14 per million — roughly 90% cheaper than fresh input, which matters if your app resends a large system prompt. Against the median priced chat model ($0.5/1M in), this sits at 2.8×.
Monthly cost examples
Assuming 1,200 prompt + 400 completion tokens per request unless noted, billed 30 days a month and without cache hits.
| Workload | Cost / month | Cost / day |
|---|---|---|
| 1,000 requests/day | $181.68 | $6.06 |
| 10,000 requests/day | $1816.8 | $60.56 |
| 100,000 requests/day | $18168 | $605.6 |
| 1M summaries/month | $14339.86 | $478 |
Model a different profile in the cost calculator.
Capabilities
Provider description
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....
Cheaper alternatives
Ranked by blended cost (3× input + 1× output) — cheaper, but check context and capabilities before switching.
| # | Model | Provider | Input $/1M | Output $/1M | Cached $/1M | Context |
|---|---|---|---|---|---|---|
| 1 | Gemini Exp 1114 | Google Gemini | free | free | — | 1.0M |
| 2 | Gemini Exp 1206 | Google Gemini | free | free | — | 2.1M |
| 3 | Gemma 3 27b It | Google Gemini | free | free | — | 131K |
| 4 | Gemma 4 26b A4b It | Google Gemini | free | free | — | 262K |
| 5 | Gemma 4 31b It | Google Gemini | free | free | — | 262K |
| 6 | Learnlm 1.5 Pro Experimental | Google Gemini | free | free | — | 33K |
Data provenance
This page is assembled from the sources below. Where two sources disagree, both are shown.
- Our input price: $1.38
- Second source: —
- Our output price: $11
- Second source: —
More from Azure OpenAI
Frequently asked
› How much does GPT 5.1 Codex cost per 1,000 tokens?
About $0.00138 for input and $0.011 for output tokens, based on the per-million rates on this page.
› Is GPT 5.1 Codex cheaper than other models?
By input price it ranks #1355 of 1809 priced chat models in this index, putting it in the more expensive half of the market.
› How often is GPT 5.1 Codex's price checked?
The dataset was last refreshed 2026-09-13 13:40 UTC. Providers can change pricing at any time — verify with Azure OpenAI before committing to a budget.