text model comparison
GPT-6 Luna vs Grok 4.3
GPT-6 Luna and Grok 4.3 are both current text models, from OpenAI and xAI. GPT-6 Luna is 92% cheaper per 1M input tokens than Grok 4.3, $0.10 vs $1.25. On Arena Text, GPT-6 Luna scores 1443 Elo and Grok 4.3 1442 Elo (Arena, measured October 8, 2026). GPT-6 Luna has the larger context window, 1,050,000 vs 1,000,000 tokens.
Data verified October 12, 2026 · Dataset 2026-10-12
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | GPT-6 Luna | Grok 4.3 |
|---|---|---|
| Price per 1M input tokens | $0.10 (better) | $1.25 |
| Price per 1M output tokens | $0.50 (better) | $2.50 |
| Cost of 10M input and 2M output tokens | $2 (better) | $17.50 |
| Arena Text | 1443 Elo (#31 of 39) (better) | 1442 Elo (#33 of 39) |
| GPQA Diamond | 90.5% (#23 of 37) (better) | 88.8% (#29 of 37) |
| FrontierMath Tiers 1-3 (v2) | 78.9% (#14 of 37) (better) | 42.8% (#32 of 37) |
| SimpleQA Verified | 41.4% (#25 of 34) (better) | 33.2% (#28 of 34) |
| Provider | OpenAI | xAI |
| Release date | September 22, 2026 | Not reported |
| Access | API only | API only |
| Context window | 1,050,000 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | Not reported |
| Input | text, image | text, image |
| 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
Grok 4.3
Best for
- General-purpose reasoning, instruction following, and agentic tool-use evaluations
Watch out for
- The published base rates double when requests reach the provider's 200,000-token long-context threshold
GPT-6 Luna vs Grok 4.3 FAQ
Which is cheaper, GPT-6 Luna or Grok 4.3?
GPT-6 Luna is 92% cheaper per 1M input tokens than Grok 4.3, $0.10 vs $1.25. For 10M input and 2M output tokens, GPT-6 Luna costs $2 and Grok 4.3 $17.50 at standard rates.
Which scores higher on independent benchmarks, GPT-6 Luna or Grok 4.3?
GPT-6 Luna leads on Arena Text, 1443 Elo to 1442 Elo; GPT-6 Luna leads on GPQA Diamond, 90.5% to 88.8%; GPT-6 Luna leads on FrontierMath Tiers 1-3 (v2), 78.9% to 42.8%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, GPT-6 Luna or Grok 4.3?
GPT-6 Luna has the larger context window, 1,050,000 vs 1,000,000 tokens.
Related comparisons
Production evaluation
Choosing between GPT-6 Luna and Grok 4.3?
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