GPT-5.6 Luna vs Solar Pro 4
GPT-5.6 Luna leads the LLM Stats Score 46.5 to 36.0. GPT-5.6 Luna is 1.2x cheaper per token.
OpenAI · Upstage · Updated for 2026
Which is better?
GPT-5.6 Luna leads the overall LLM Stats Score 46.5 to 36.0, ranking #21 overall.
In the 3 individual benchmarks reported for both models, GPT-5.6 Luna wins 3; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-5.6 Luna is roughly 1.2x 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 GPT-5.6 Luna
- overall performance matters — it scores 46.5 and ranks #21 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 3 of 3 exact shared results
- cost matters — it's about 1.2x cheaper per token
- you process long inputs — it offers a 1,050,000 token context window
Choose Solar Pro 4
- you want the most recent training data — it shipped Aug 2026
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
44 reported for GPT-5.6 Luna · 9 for Solar Pro 4
GPT-5.6 Luna outperforms in 3 benchmarks (BrowseComp, GPQA, Terminal-Bench 2.1), while Solar Pro 4 is better at 0 benchmarks.
GPT-5.6 Luna 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, GPT-5.6 Luna ($0.20/1M tokens) is 1.5x cheaper than Solar Pro 4 ($0.30/1M tokens).
For output processing, GPT-5.6 Luna ($1.20/1M tokens) costs the same as Solar Pro 4 ($1.20/1M tokens).
In conclusion, Solar Pro 4 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 Solar Pro 4's 524,288 tokens. Solar Pro 4 can generate longer responses up to 131,072 tokens, while GPT-5.6 Luna is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
GPT-5.6 Luna supports multimodal inputs, whereas Solar Pro 4 does not.
GPT-5.6 Luna can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.6 Luna
Solar Pro 4
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
GPT-5.6 Luna was released on 2026-07-09, while Solar Pro 4 was released on 2026-08-06.
Solar Pro 4 is 1 month newer than GPT-5.6 Luna.
Jul 9, 2026
1 months ago
Aug 6, 2026
3 weeks ago
4w newerKnowledge Cutoff
When training data ends
GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Solar Pro 4's cutoff date is not specified.
We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Solar Pro 4's cutoff date.
Feb 2026
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Provider Availability
GPT-5.6 Luna is available from OpenAI. Solar Pro 4 is available from Upstage.
GPT-5.6 Luna
Solar Pro 4
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.6 Luna and Solar Pro 4 side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.6 Luna vs Solar Pro 4.