GPT-5.1 Codex vs GPT-5.6 Luna
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.6 Luna by OpenAI wins on 5 of 5 benchmarks against GPT-5.1 Codex by OpenAI, which leads on 0. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
Reasoning: In reasoning, GPT-5.6 Luna scores 87.7% on GPQA Diamond compared to GPT-5.1 Codex's 65.0%.
Context: In context, GPT-5.6 Luna scores 1.1M on Context Length compared to GPT-5.1 Codex's 400K.
Pricing Comparison
GPT-5.1 Codex costs $1.3/1M input tokens and $10.0/1M output tokens, while GPT-5.6 Luna costs $0.20/1M input and $1.2/1M output. GPT-5.6 Luna is the more affordable option for API usage.
Verdict
GPT-5.6 Luna leads across the board in affordability, making it the stronger overall choice in this comparison.
View Individual Model Pages
GPT-5.1 Codex vs GPT-5.6 Luna — FAQ
Which is better, GPT-5.1 Codex or GPT-5.6 Luna?
GPT-5.6 Luna wins on more benchmarks overall (5 vs 0). However, the best choice depends on your specific needs — each model excels in different areas.
How does GPT-5.1 Codex compare to GPT-5.6 Luna for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is GPT-5.1 Codex cheaper than GPT-5.6 Luna?
Yes, GPT-5.6 Luna is cheaper. GPT-5.1 Codex costs $1.3/1M input and $10.0/1M output tokens. GPT-5.6 Luna costs $0.20/1M input and $1.2/1M output tokens.
Which is faster, GPT-5.1 Codex or GPT-5.6 Luna?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the GPT-5.1 Codex vs GPT-5.6 Luna comparison cover?
This comparison covers 5 benchmarks including GPQA Diamond, Input Cost, Output Cost, Context Length, Cached Input Cost. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.