GPT-5.1-Codex-Max is $3.75 cheaper per 1M input tokens (75% lower; 4x difference).
API cost decision in 10 seconds
GPT-5.1-Codex-Max vs Claude Opus 4.5
Pick GPT-5.1-Codex-Max when budget and context both matter.
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Data confirmed:
Prices normalized to USD per 1M tokens
Sample workload: 1M input + 500K output
Budget verdict
Pick GPT-5.1-Codex-Max when budget and context both matter.
On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Max is estimated at $6.25 vs $17.5 for Claude Opus 4.5, saving $11.25 (64.3% lower).
Cost-first pickGPT-5.1-Codex-Max
Context-first pickGPT-5.1-Codex-Max
Sample savings$11.2564.3%
10x traffic gap$112.5
GPT-5.1-Codex-Max is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $112.5. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
GPT-5.1-Codex-Max stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | GPT-5.1-Codex-Max | Claude Opus 4.5 |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | GPT-5.1-Codex-Max | $11.25 | $37.5 |
| Balanced workload | 1M input + 1M output | GPT-5.1-Codex-Max | $11.25 | $30 |
| Output-heavy chatbot | 1M input + 5M output | GPT-5.1-Codex-Max | $51.25 | $130 |
GPT-5.1-Codex-Max is $15 cheaper per 1M output tokens (60% lower; 2.5x difference).
GPT-5.1-Codex-Max has 200K more context (2x larger).
GPT-5.1-Codex-Max is $11.25 cheaper on the standard workload (64.3% lower).
Estimate your workload cost
Your Workload Cost
This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.
Quick Decision
GPT-5.1-Codex-Max has the lower input price; GPT-5.1-Codex-Max has the lower output price; GPT-5.1-Codex-Max offers the larger context window. For the 1M input plus 500K output sample, GPT-5.1-Codex-Max is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $6.25 for GPT-5.1-Codex-Max and $17.5 for Claude Opus 4.5.
Choose GPT-5.1-Codex-Max when you care most about lower input-token price, lower output-token price, and larger context window.
Choose Claude Opus 4.5 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.
- On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Max is estimated at $6.25 vs $17.5 for Claude Opus 4.5, saving $11.25 (64.3% lower).
- GPT-5.1-Codex-Max is $11.25 cheaper on the standard workload (64.3% lower).
- GPT-5.1-Codex-Max is $3.75 cheaper per 1M input tokens (75% lower; 4x difference).
- GPT-5.1-Codex-Max is $15 cheaper per 1M output tokens (60% lower; 2.5x difference).
- GPT-5.1-Codex-Max has 200K more context (2x larger).
| Feature | GPT-5.1-Codex-Max (OpenAI) | Claude Opus 4.5 (Anthropic) |
|---|---|---|
| Input Price prompt tokens per 1M | $1.25 | $5 |
| Completion Price per 1M tokens | $10 | $25 |
| Sample Workload Cost 1M input + 500K output | $6.25 | $17.5 |
| Context Window | 400K | 200K |
| Release Date |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | GPT-5.1-Codex-Max | On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Max is estimated at $6.25 vs $17.5 for Claude Opus 4.5, saving $11.25 (64.3% lower). |
| High-volume input processing | GPT-5.1-Codex-Max | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | GPT-5.1-Codex-Max | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | GPT-5.1-Codex-Max | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- gpt-oss-120b (free) can replace GPT-5.1-Codex-Max when lower sample workload cost matters most: $0.
- gpt-oss-20b (free) can replace GPT-5.1-Codex-Max when lower sample workload cost matters most: $0.
- gpt-oss-20b can replace GPT-5.1-Codex-Max when lower sample workload cost matters most: $0.1.
- gpt-oss-120b can replace GPT-5.1-Codex-Max when lower sample workload cost matters most: $0.13.
- Llama 4 Scout offers 10M context with $0.23 sample workload cost.
- Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
- Grok 4.20 offers 2M context with $2.5 sample workload cost.
- GPT-5.5 offers 1.05M context with $20 sample workload cost.
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