GPT-5.4 is OpenAI’s latest frontier model, unifying the Codex and GPT lines into a single system. It features a 1M+ token context window (922K input, 128K output) with support for...
Model details →OpenAI: GPT-5.4 vs OpenAI: GPT-5.6 Luna Pro
OpenAI: GPT-5.6 Luna Pro wins on 2 of 6 axes — pricing and capability skew in its favour for most workloads.
GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://devel…
Model details →Side-by-side comparison
| Capability | OpenAI: GPT-5.4 | OpenAI: GPT-5.6 Luna Pro | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 1.1M | 1.1M | Tie |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $2.50 | $0.10 | 🏆 OpenAI: GPT-5.6 Luna Pro |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $15.00 | $0.60 | 🏆 OpenAI: GPT-5.6 Luna Pro |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | Yes | Yes | Tie |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is OpenAI: GPT-5.4 better than OpenAI: GPT-5.6 Luna Pro?
OpenAI: GPT-5.6 Luna Pro wins on 2 of 6 axes — pricing and capability skew in its favour for most workloads.
What's the price difference between OpenAI: GPT-5.4 and OpenAI: GPT-5.6 Luna Pro?
Input: $2.50 vs $0.10 per 1M tokens. Output: $15.00 vs $0.60 per 1M tokens.
What context windows do OpenAI: GPT-5.4 and OpenAI: GPT-5.6 Luna Pro support?
OpenAI: GPT-5.4 supports up to 1.1M tokens. OpenAI: GPT-5.6 Luna Pro supports up to 1.1M tokens.
Do both OpenAI: GPT-5.4 and OpenAI: GPT-5.6 Luna Pro support tool calling?
OpenAI: GPT-5.4: yes. OpenAI: GPT-5.6 Luna Pro: yes.
Compare OpenAI: GPT-5.4 with other models
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