Claude Sonnet 5.5 vs GPT-5.6 Luna
Claude Sonnet 5.5 leads the LLM Stats Score 58.7 to 44.2. GPT-5.6 Luna is 8.9x cheaper per token.
Anthropic · OpenAI · Updated for 2026
Which is better?
Claude Sonnet 5.5 leads the overall LLM Stats Score 58.7 to 44.2, ranking #2 overall.
In the 9 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 9; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-5.6 Luna is roughly 8.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Claude Sonnet 5.5
- overall performance matters — it scores 58.7 and ranks #2 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 9 of 9 exact shared results
- you want the most recent training data — it shipped Sep 2026
Choose GPT-5.6 Luna
- cost matters — it's about 8.9x cheaper per token
- you process long inputs — it offers a 1,050,000 token context window
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
47 reported for Claude Sonnet 5.5 · 45 for GPT-5.6 Luna
Claude Sonnet 5.5 outperforms in 9 benchmarks (AutomationBench, BenchCAD, BenchCAD (with Python tool), DeepSWE 1.1, FrontierCode 1.1, HealthBench, HealthBench Professional, SWE-Bench Pro, Terminal-Bench 4.0), while GPT-5.6 Luna is better at 0 benchmarks.
Claude Sonnet 5.5 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Sonnet 5.5 ($2.00/1M tokens) is 10.0x more expensive than GPT-5.6 Luna ($0.20/1M tokens).
For output processing, Claude Sonnet 5.5 ($10.00/1M tokens) is 8.3x more expensive than GPT-5.6 Luna ($1.20/1M tokens).
In conclusion, Claude Sonnet 5.5 is more expensive than GPT-5.6 Luna.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.6 Luna accepts 1,050,000 input tokens compared to Claude Sonnet 5.5's 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Sonnet 5.5 and GPT-5.6 Luna support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Sonnet 5.5
GPT-5.6 Luna
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Sonnet 5.5 was released on 2026-09-28, while GPT-5.6 Luna was released on 2026-07-09.
Claude Sonnet 5.5 is 3 months newer than GPT-5.6 Luna.
Sep 28, 2026
2 weeks ago
2mo newerJul 9, 2026
3 months ago
Knowledge Cutoff
When training data ends
Claude Sonnet 5.5 has a knowledge cutoff of 2026-06-01, while GPT-5.6 Luna has a cutoff of 2026-02-16.
Claude Sonnet 5.5 has more recent training data (up to 2026-06-01), making it potentially better informed about events through that date compared to GPT-5.6 Luna (2026-02-16).
Jun 2026
4 mo newerFeb 2026
Provider Availability
Claude Sonnet 5.5 is available from Anthropic. GPT-5.6 Luna is available from OpenAI.
Claude Sonnet 5.5
GPT-5.6 Luna
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Sonnet 5.5 and GPT-5.6 Luna side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Sonnet 5.5 vs GPT-5.6 Luna.