Grok 4.5: xAI's 500k-Context Model
Key facts · verified Oct 29, 2026
Grok 4.5 is a SpaceXSI model released on 16 Jul 2026. Its API price is $2 per million input tokens and $6 per million output tokens (<200k prompts; $4 / $12 at 200k+). Its context window is 500k tokens. It ranks #53 on LMArena's text leaderboard (Elo 1465, read 3 Nov 2026). Source: docs.x.ai.
xAI's Grok 4.5, with a 500k token context window. Pricing is tiered by prompt length: $2 input / $6 output per 1M tokens under 200k tokens, doubling to $4 / $12 at or above 200k.
Key Features
What is Grok 4.5?
Grok 4.5 is a model from xAI with a 500,000 token context window. Pricing is tiered by prompt length: $2 input and $6 output per million tokens below 200k tokens, doubling to $4 and $12 at or above that threshold.
What xAI Does Not Publish
xAI's model and pricing documentation covers context window and API pricing only. It does not state a parameter count, an architecture, a release date, or capabilities such as tool use, vision or agentic features, so this guide does not assert any of them.
Context Window
Grok 4.5 has a 500,000 token context window - half the 1 million tokens of Claude Opus 5, and below GPT-5.6's 1.05 million.
Weights
xAI does not publish weights for Grok 4.5.
Ranking and Price Against Other Models
On LMArena's text leaderboard Grok 4.5 has 1465 Elo (rank 53); Claude Opus 5 has 1492 Elo (rank 14, high effort), Gemini 3.1 Pro 1487 Elo (rank 20), GPT-5.6 Sol 1485 Elo (rank 22, xhigh effort), DeepSeek V4-Pro 1458 Elo (rank 65) and Mistral Large 3 1414 Elo (rank 146). Published API prices per million input / output tokens: Grok 4.5 $2 / $6 under 200k tokens, Claude Opus 5 $5 / $25, GPT-5.6 Sol $4 / $20 (OpenAI's promotional price).
Key Takeaways
- xAI publishes no parameter count or architecture detail for Grok 4.5
- 500K token context window
- Tiered pricing: $2/$6 per million tokens below 200k tokens, $4/$12 at or above
- LMArena: 1465 Elo (rank 53)
Official Resources
Full Specifications
$2 / $6 per million tokens | |
|---|---|
| Identity | |
| Developer | SpaceXSI |
| Released | Jul 2026 |
| Status | GA |
| Licence | Proprietary |
| Self-hostable | No |
| Cost | |
| Blended $/1M tokensinput × 0.75 + output × 0.25 | $3.000 / 1M tokens |
| Input price | $2.000 / 1M tokens |
| Output price | $6.000 / 1M tokens |
| Cached input | $0.30 / 1M tokens (<200k tier); $0.60 / 1M tokens (>=200k tier) |
| Batch discount | Not offered |
| Free tier | Not offered |
| Capacity | |
| Context window | 500k tokens |
| Long-context surcharge | 2x input / 2x output at/above 200k prompt tokens |
| Capability | |
| Vision in | Yes |
| Audio in | Not offered |
| Function calling | Yes |
| Structured output | Yes |
| Extended reasoning | Yes |
| Web search | Not offered |
| Code execution | Not offered |
| Access | |
| API | Yes |
| Chat app | Yes |
| Cloud marketplaces | Not offered |
| Fine-tuning | Not offered |
| Measured quality | |
| LMArena Elo | 1465 (checked Nov 2026) |
| LMArena rank | Rank 53 |
| GPQA Diamond | 93 · high effort |
| Elo per dollarLMArena Elo ÷ blended $/1M tokens | 488 |