text model comparison
GPT-6 Luna vs Solar Pro 4
GPT-6 Luna and Solar Pro 4 are both current text models, from OpenAI and Upstage. GPT-6 Luna is 67% cheaper per 1M input tokens than Solar Pro 4, $0.10 vs $0.30. On Arena Text, GPT-6 Luna scores 1443 Elo and Solar Pro 4 1386 Elo (Arena, measured October 8, 2026). GPT-6 Luna has the larger context window, 1,050,000 vs 512,000 tokens.
Data verified October 13, 2026 · Dataset 2026-10-13
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | GPT-6 Luna | Solar Pro 4 |
|---|---|---|
| Price per 1M input tokens | $0.10 (better) | $0.30 |
| Price per 1M output tokens | $0.50 (better) | $1.20 |
| Cost of 10M input and 2M output tokens | $2 (better) | $5.40 |
| Arena Text | 1443 Elo (#37 of 49) (better) | 1386 Elo (#45 of 49) |
| GPQA Diamond | 90.5% (#25 of 40) | Not measured |
| FrontierMath Tiers 1-3 (v2) | 78.9% (#14 of 40) | Not measured |
| SimpleQA Verified | 41.4% (#26 of 36) | Not measured |
| Provider | OpenAI | Upstage |
| Release date | September 22, 2026 | August 6, 2026 |
| Access | API only | API only |
| Context window | 1,050,000 tokens | 512,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Input | text, image | text |
| Output | text | text |
When to choose each
GPT-6 Luna
Best for
- High-volume summarisation, extraction and routing
- Long-context budget work, where the 272k threshold is more forgiving than Haiku 5.5's 100k
Watch out for
- Prompts over 272,000 tokens are rebilled at $0.20 input and $0.75 output for the whole request
- A twentieth of GPT-6 Sol's price reflects a capability gap, not a discount on the same model
Solar Pro 4
Best for
- Korean and Japanese enterprise workloads
- Multi-step agent work with tool calls
Watch out for
- A closed model: Upstage does not disclose its parameter count
- Several of its published benchmark figures are in-house evaluations
GPT-6 Luna vs Solar Pro 4 FAQ
Which is cheaper, GPT-6 Luna or Solar Pro 4?
GPT-6 Luna is 67% cheaper per 1M input tokens than Solar Pro 4, $0.10 vs $0.30. For 10M input and 2M output tokens, GPT-6 Luna costs $2 and Solar Pro 4 $5.40 at standard rates.
Which scores higher on independent benchmarks, GPT-6 Luna or Solar Pro 4?
GPT-6 Luna leads on Arena Text, 1443 Elo to 1386 Elo. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, GPT-6 Luna or Solar Pro 4?
GPT-6 Luna has the larger context window, 1,050,000 vs 512,000 tokens.
Related comparisons
Production evaluation
Choosing between GPT-6 Luna and Solar Pro 4?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty