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OpenAIGPT-5.4 ProVSOpenAIGPT-5.6 Luna

Analysis by:the whichllmmodel Editorial Team|Updated: June 2026

Our Take

Standardized reasoning and coding benchmarks are currently pending verification for one or both of these models. We recommend testing GPT-5.4 Pro and GPT-5.6 Luna directly in their respective provider playgrounds to see which fits your specific prompt styles best.
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Model Specs

GPT-5.4 Pro

Benchmarks & Scores

Coding (swe-bench-pro)
N/A

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)
67.6%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)16.4x cheaper
$0.14Input: $0.05 | Output: $0.40
Context Window
400k tokens
Model Specs

GPT-5.6 Luna

Benchmarks & Scores

Coding (swe-bench-pro)
62.7%

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)Winner (+24.7%)
92.3%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)
$2.25Input: $1.00 | Output: $6.00
Context WindowLarger
1.05M tokens

Frequently Asked Questions about GPT-5.4 Pro vs GPT-5.6 Luna

GPT-5.4 Pro is cheaper than GPT-5.6 Luna. GPT-5.4 Pro has a blended cost of $0.14/1M tokens, which is about 16.4x cheaper than GPT-5.6 Luna at $2.25/1M tokens.

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