whichllmmodel
Back to Dashboard

OpenAI GPT-5.5 VS OpenAI GPT-5.6 Luna

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

Decision Recommendation

⚖️ Editorial Verdict: In our analysis, GPT-5.6 Luna is the premium intelligence choice, scoring 4.1% higher on coding benchmarks. It also maintains strong cost efficiency. If you are building high-volume, simple chatbots or processing massive amounts of text where budget is critical, GPT-5.5 offers excellent cost savings. For agentic reasoning, code refactoring, or complex logical tasks, the accuracy premium of GPT-5.6 Luna fully justifies the cost.
Was this recommendation helpful?
Model Specs

GPT-5.5

Benchmarks & Scores

Coding (swe-bench-pro)
58.6%

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

Reasoning (gpqa-diamond)Winner (+1.3%)
93.6%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)
$11.25Input: $5.00 | Output: $30.00
Context Window
1.05M tokens
Model Specs

GPT-5.6 Luna

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+4.1%)
62.7%

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

Reasoning (gpqa-diamond)
92.3%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)5.0x cheaper
$2.25Input: $1.00 | Output: $6.00
Context Window
1.05M tokens

Frequently Asked Questions about GPT-5.5 vs GPT-5.6 Luna comparison

GPT-5.6 Luna is cheaper than GPT-5.5. GPT-5.6 Luna has a blended cost of $2.25/1M tokens, which is about 5.0x cheaper than GPT-5.5 at $11.25/1M tokens.

GPT-5.6 Luna is better for coding tasks on this benchmark. It scores 62.7% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) compared to GPT-5.5 which scores 58.6%.